Please explain if it is possible to have surgery if only one ball/testicule dropped?

Undescended testis. Surgery is recommended for undescended testicles to prevent testicular cancer or at least decrease the increased risk. Please contact a urologist or general surgeon. The surgery is called orchipexy.
Orchipexy. Are you asking about orchipexy which is surgery to find undescended testicle (cryptorchidism)? Or do you want to know if one testicle will prevent you from having surgery like hair transplant, hip replacement or cataract extraction. Answer to latter perspective is no. If I didn't interpret your question as you intended, please write back w/more details or wait for my colleagues to answer.