I'm assuming English isn't your first language but trying to understand what's going on - you have a dog who is basically out of control and your options include castration, according to your vet? Well if you think that's a cure-all, think again. It's not. It will only prevent him siring unwanted litters of puppies, assuming he can get out. Sleeping all day - what with tranquilisers? No way! That's no life for a dog, for starters.
Feeding him what? Nuts? Never heard of that, for improving anything!!
For me, you have two options, euth. or finding him a home with people who can train and live with him? Obviously I'd opt for the finding a more suitable home - IF POSSIBLE!!
What breed? As for age, 4 is NOT old for any dog.