Wanted: one teen-ager . . .

Five months ago, after ten years of marriage and no children, we greeted our first ''son.'' Six feet tall, 16 years old, and carrying a ''ghetto blaster'' as he got off the plane.

My husband's sister had called a few nights earlier from 2,000 miles away. Her son, our nephew, had dug himself a deep hole, jumped in, and now he wanted out. It seemed that it would be easier for him to ''get out'' if he started fresh in a new place.

''Can he come live with you for a while?''

''Sure,'' we said, both of us on different phones, but looking at each other and nodding yes, of course, why not. But we really didn't think it would happen.

The next night, another call. ''Pick him up tomorrow on a 5 o'clock flight.'' We were too dazed to speak. When I got off the phone, I let out a muffled scream.

So the next day, we picked him up at the airport. Him, his music machine (little did we realize then that rock music would become our household Muzak), his TV, video games, water bed, cassettes, albums, clothes, etc. We brought him home.

Home. A four-family remodeled 1820s Colonial on the main street of a New England town of 4,000. His former home? A suburb of 100,000, where he had his own car and lived in a neighborhood of look-alike shipshape brick split-levels.

But don't worry, nephew. Our state has more cows than people, ha ha. He didn't laugh.

We told him we lived in an apartment (true) and that there was an outhouse out back (untrue). Again, he couldn't quite laugh. Was this a joke, and were we for real? No, ha ha. We don't have an outhouse. But there is a community bathroom for the whole house. And we all have assigned hours for using the shower. Yours are 6:30-7 a.m. Poor nephew. He was on the verge of breaking out in a cold sweat.

His first morning, Fred and I went off to jobs, so nephew got to wake up leisurely (he always woke up leisurely) and explore the town on his own. When I arrived home, I was frantically greeted with (besides the rock music): ''I walked three blocks this way, three blocks that way, and there's nuthin' to do! I gotta get outta here! This place will drive me crazy!''

But somehow he survived his initial shock and stayed. After a few more ''exciting'' days on his own, the thought of enrolling in school didn't sound too bad. But it was soooo small! Grades 1-12 all in one school! You had to watch where you stepped so you didn't crush a first-grader! And the principal? Out to get him! The girls? Not enough! (So who were all those girls suddenly calling on our phone, nephew?)

We allocated some jobs to him. If he brought in the wood for the wood stove, I would do his laundry at the laundromat up the street. Deal. But gradually, somehow, it slipped his mind that this was his job. So he got to do his own laundry, and I brought in the wood once again. That was fine with me. I was tired of spending extra time at the laundromat waiting for his week's supply of jeans to dry.

He cooked one night a week. It was always Chef Boy-Ar-Dee Pizza Mix, every Wednesday night, which was fine with us. He theoretically did the dishes every third night, but in actuality, we never got that part very well organized. ''Whose night is it?'' ''I did them last night.'' ''No, I did.'' ''It's your turn.'' ''No way!''

I did the grocery shopping for the three of us. Nephew likes a lot of junk food. I do too, but I don't buy it, so I won't eat it. I always dreaded bumping into someone familiar with a cart full of fresh vegetables, milk, and eggs, while I pushed my grocery cart down the aisle filled with brilliant orange fat cheese chips, donuts, soda, and strawberry-flavored, sugar-and-sprinkles-coated Pop Tarts. (''Oh, this stuff isn't for me. It's for my nephew.'')

The first time we all drove over to visit my folks an hour away, we took our regular two-lane road, and stopped at some of the antique shops in the old Colonials along the way. Nephew asked if we could take the main road back. ''This is the main road, nephew.''

And the music. Oh yes, the music! Fred rented a little office space a few blocks away so he could continue to think. I ''rented'' a stool every morning at a local cafe where I could go, be alone, and read my newspaper. But did I ever learn a lot! Every time a favorite song of nephew's came on the radio (and he had numerous favorites), he would ask me, ''Who sings this one?''

(Duh.) ''What does it begin with?''

''J!'' (As he wildly plays an imaginary electric guitar while mouthing the words to the song.)

''Journey!''

''All right!''

I got pretty good at it, as long as he gave me the first letter.

He taught me how to ride a motorcycle. He even had the courage to be my first back-seat passenger. He and Fred laughed at each other's good and terrible jokes. We enjoyed his good friend a lot, too. We called them ''the boys,'' though not to their faces, of course.

And he did learn to be more responsible. We had a few conferences with the school principal, but he did get himself there every day, even though Fred and I were gone by school time. Where he had been earlier, he had stopped going to school. And he did come home every night, also something that hadn't been happening before very regularly.

And then he left, just about as suddenly as he had come. School ended. He started feeling that he would be able to handle things back home. Time to go water-skiing. Have a little more action. See his friends. We made plane reservations, and he was gone in a week.

That was five days ago. Since Fred now has his office, I'm taking over nephew's room as my studio room. But we did consider putting an ad in the paper. ''Wanted. One teen-ager ready to reform.''