DEAR ABBY: I have a serious problem with my best friend. "Jennifer" and I used to tell each other everything, and I thought our friendship would be forever. But recently I have not been able to understand her at all.

Jennifer has started using drugs. I knew she was smoking pot, but she had promised me she wouldn't do anything heavier. Now I know she was lying to me. I've tried to get her to quit, but it's getting worse every day. We argue a lot and sometimes she swears at me. (She never did that before she was on drugs.)

We are students, and I can't study because I'm so worried about her.

Two weeks ago I decided I couldn't stand it any more and made a decision to stay away from her. I still would like to be Jennifer's friend because I remember what a sweet girl she used to be. But now I don't know if I even like her. Even though I feel freedom after separating from her, I worry that maybe I'm making her life worse by not being there for her when she needs me.

Abby, should I still be a friend of hers or not? -- CONFUSED IN CALIFORNIA

DEAR CONFUSED: Your friend is in serious trouble, and if you continue to keep her drug use a secret, you will be letting her down. She needs help. And the way to see that she gets it is to tell your parents, or a trusted teacher or school counselor what's going on. This is not the same thing as tattling -- you would be helping to save her life.

I recently printed a letter from the mother of a young man who had overdosed on drugs. That letter, and the accompanying piece, "King Heroin," produced an outpouring of mail from addicts and alcoholics, as well as from their families and friends.

A strong message of hope came from those who had found recovery in a 12-step program. Read on for a sample:

DEAR ABBY: I'm almost 50 years old and I had only heard of miracles, but had never experienced one. My daughter suffered from drug addiction for almost six years. During those six years, our lives were a living hell. I ranted, raved, threatened and bribed repeatedly, all to no avail.

After hitting rock bottom physically, spiritually and emotionally, she stumbled into a meeting of a 12-step program. She took one step and one day at a time. Through her belief in the program and the guidance of her sponsor, she restored her life to sanity.

She knows there is no cure for her addiction, but there is recovery. This month, she will celebrate her second year as a recovering addict. That is a miracle!

For those who suffer from addiction or have friends or family who are addicted, there is hope. If you attend a meeting of a 12-step program, you too can experience a miracle. -- MOTHER OF A MIRACLE

DEAR MOTHER (AND ALL WHO WROTE WITH A SIMILAR STORY): Your message of hope is worth repeating. Twelve-step programs have worked when all else has failed. The most well-known programs are: Alcoholics Anonymous, Narcotics Anonymous, Al-Anon Family Groups (for friends and family members), and Alateen (for young friends and family members). Check your local phone directory or newspaper for meeting locations, or write to: Alcoholics Anonymous, General Service Office, 475 Riverside Drive, 11th Floor, New York, N.Y. 10115; Al-Anon and Alateen, 1600 Corporate Landing Parkway, Virginia Beach, Va. 23454-5617; Narcotics Anonymous, World Service Office, 19737 Nordhoff Place, Chatsworth, Calif. 91311.

For everything you need to know about wedding planning, order "How to Have a Lovely Wedding." Send a business-sized, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: Dear Abby, Wedding Booklet, P.O. Box 447, Mount Morris, Ill. 61054-0447. (Postage is included.)

DEAR ABBY: I've never written before, but I'm sure you'll receive a lot of mail about the letter you printed from "Young Mother in Pennsylvania." She wrote, "I know Claire better than anyone else, so shouldn't I know the best way to be a parent to her?" Your answer was, "Yes, stick to your convictions."

I believe you overlooked a few things when you gave that answer. First of all, she's married at 19, they're living with her parents until they can get on their feet, and they have a 9-month-old child. It appears they entered the marriage without considering the costs of living together as a married couple, and to complicate matters, they had a child within the first year. (I'm not even considering the possibility of conception before marriage.)

However you look at it, this constitutes lack of wisdom.

She also said that although both of their parents "did a good job in raising them," now she suddenly feels she knows more than they do because she "knows her child." Abby, loving her child and being with her doesn't equate with wisdom in raising a child.

The problem appears to lie in her statement, "... what seems like advice to them sounds like criticism to me." Her viewpoint needs a little readjustment!

Granted, not all of their suggestions may be the best, but that doesn't mean she should throw the combined total of 40 years' experience out the window. She should sift through it and apply what appears reasonable. She should also be grateful for their advice and realize that they want what's best for both her and the grandchild because they love them. Viewing it from that perspective will help her gain wisdom and cope with the situation until they can move out on their own. -- SECOND OPINION FROM MINNESOTA

DEAR SECOND OPINION: You're right on all counts. I received considerable criticism for taking the side of the 19-year-old mother who wanted to tune out her parents' and in-laws' advice on child-rearing. Read on:

DEAR ABBY: When I saw the letter from the "Young Mother in Pennsylvania" who was receiving unwanted advice on how to raise her baby daughter, I felt compelled to write.

My mother taught me a magic phrase many years ago to help me deal with a relative who also gave a lot of unsolicited advice.

The phrase is: "It's something to think about." It gives the person giving the advice the feeling that you value his or her opinion. And it allows the listener to graciously take heed -- or let it go in one ear and out the other.

I wish the young mother much luck. -- EDIE CHERNACK, VERNON, CONN.

DEAR EDIE: Your tactful mother gave you excellent advice.

DEAR ABBY: When I became engaged, my future mother-in-law gave me a lovely diamond ring that had been in her family for three generations. I was thrilled and have cherished it. I know that it is worth several thousand dollars.

I am now divorced, and she has asked me to please return the ring. I love her very much and couldn't refuse her or fight over it, but that ring means a lot to me. I would have had the stone reset or, perhaps, passed it down to my children.

What is the right thing to do? -- DOUBLY BROKENHEARTED

DEAR BROKENHEARTED: Since your former mother-in-law has asked you to return this family keepsake that has been in the family for three generations, the "right" thing to do would be to return it.

DEAR ABBY: When I became engaged, my future mother-in-law gave me a lovely diamond ring that had been in her family for three generations. I was thrilled and have cherished it. I know that it is worth several thousand dollars.

I am now divorced, and she has asked me to please return the ring. I love her very much and couldn't refuse her or fight over it, but that ring means a lot to me. I would have had the stone reset or, perhaps, passed it down to my children.

What is the right thing to do? -- DOUBLY BROKENHEARTED

DEAR BROKENHEARTED: Since your former mother-in-law has asked you to return this family keepsake that has been in the family for three generations, the "right" thing to do would be to return it.

DEAR ABBY: Please advise all parents to take time RIGHT NOW to show their children how to place a collect call from a pay phone.

Our 9-year-old son attended his school basketball game and was to have been brought home by his coach. Well, the coach forgot him. So our son thought the best way to handle the situation was to start walking!

We were alarmed when he did not show up at the expected time and went looking for him, but somehow we missed him. Fortunately, he knew his way home and arrived safely, but not until 9:30 p.m. Had he known how to make a collect call, we could have been saved a lot of grief.

From now on, our children will always have money for a phone call, and they now know how to dial collect.

Also, if you have volunteered to be responsible for any child, be sure to uphold your end of the bargain and see that the child gets home safely. -- RELIEVED PARENTS, LA HABRA, CALIF.

DEAR RELIEVED PARENTS: Thank you for a valuable letter. When children are involved, it's a good idea to have an alternate "game plan" for every situation. No child should walk alone after dark. In most (but not all) cities, simply dialing "0" for operator from a pay phone will put the child in touch with assistance. Parents: Find out what's required to dial a collect local call and teach your children today.

DEAR ABBY: My daughter's husband had two children with his first wife, and then had a vasectomy. Now he and my daughter want to have a family of their own. He has tried three times to have the vasectomy reversed, without success. In vitro fertilization costs more than they can afford.

They are considering using sperm from her husband's brother to impregnate my daughter. The brother's wife has agreed. Have you ever heard of this arrangement? Has it worked successfully? -- WONDERING FAMILY

DEAR WONDERING FAMILY: I have heard of this arrangement and others similar to it. It is important for all concerned to remember that the commitments required from everyone are lifelong.

If your daughter and son-in-law have not already done so, they would be wise to consult a fertility expert about their alternatives. A counselor who is familiar with infertility and family dynamics could also be helpful, as well as an attorney with expertise in family law.

DEAR ABBY: I work at a public library, and a patron has a question about whether she should receive a thank-you note for a hostess gift she took to a young couple's house. The expensive box of candy was put out by the young couple, but most was saved for later.

The patron said she wrote a note the next day, thanking them for the evening. Should she expect a note of thanks for the candy? -- S.H. IN FLORIDA

DEAR S.H.: A hostess gift is usually a token of gratitude for the effort made to entertain the guest. I see no reason why the guest should expect a thank-you note for her thank-you.

What teens need to know about sex, drugs, AIDS, and getting along with peers and parents is in "What Every Teen Should Know." To order, send a business-sized, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: Dear Abby, Teen Booklet, P.O. Box 447, Mount Morris, Ill. 61054-0447. (Postage is included.)