1. To no longer communicate with someone regularly. In this usage, "lose touch" is a set phrase. Unfortunately, my college roommate and I lost touch over the years, so I have no idea how she's doing now.
2. To no longer be skilled in doing something. In this usage, a noun or pronoun is used between "lose" and "touch." The students no longer listen to my threats—I must be losing my touch.
lose one's touch (with someone or something)
Fig. to lose one's ability to handle someone or something. I seem to have lost my touch with my children. They won't listen to me anymore. We've both lost our touch as far as managing people goes.
Fail to keep in contact or communication, as in The two sisters lost touch years ago, or Please don't lose touch with me after you move away. [Late 1800s] For an antonym, see in touch.