Do you think I should ask my uncle to finally help me out?
I think you should, but why haven't you asked him for help in the past?
He's not very good at anything and he never seems to want to help me.
If you think your uncle can help you then you should ask. It sounds like you may not be happy with his help even if he gives it. Try to be patient and appreciative for any help he gives you.
I'll try to give him another chance to do better, but it probably won't matter.
I see how frustrated you are with your uncle, but maybe he doesn't understand the instructions that you give? Try to give him very specific task instructions and see how he does.