I did hydrocele operation , one side , it is now day 11 , and swelling reduced well , can i go back to gym play bodybuilding and lifting heavy weight?

Post OP Norms: Yes. It sure sounds like it. I am sure your surgeon gave you some instructions regarding this. So, if they have anything different than this i would first have you follow their advice. But, as long as your pain free and able to be active without pain then go for it.

As surgeon advised: 11 days after surgery seems a lttle too early to resume all your physical activities. Your surgeon is best person to advise. I would suggest you wear supportive underwear or compression short pants like lycra to reduce risk of scrotal swelling. Good luck.