I had an operation on my stomach, it has been 5 months, however I lost 10 Kgs weight and left the exercise, I am going to back to lift weighting but I am still worried I can not recover my weights, the doctor could not advise me.

Couldn't advise you on... what? Whether you will regain the weight or regain your ability to lift weights?

I agree... what's the problem exactly?

Sounds like you had a surgery and you lost weight. You want to put muscle weight back on through lifting but the doc said no??