lose one's touch

مهارت خود را در انجام کاری از دست دادن

to no longer be able to do something well

EXAMPLE 1: I used to make delicious pies, but this one tastes terrible. I think I've lost my touch.

EXAMPLE 2: Dr. Stewart used to be a very good doctor, but recently several of his patients have died. He seems to have lost his touch!