Cannot is formal, while can't in informal.
"Cannot" and "can not" are interchangeable, but when you are asking question for example:
"why can't I...", you can also say "why can I not..." (which is more formal), but you can't say "why cannot I..."
He said he would like it if you guys can come over to see him and he will come help with me the way I want him and I can tell you that he’s a good man but he’s uuuu and he hates him so he is so sad that he’s a man he’s not even hurt he’s like he’s so tired
