“Can anyone prove that you have a brain??”
Sure.  List the behaviors of people who do not have a functioning brain, and the behaviors that require a brain.  Which list describes me?  
That was easy.
“We dont see it, feel it, OR hear it..”
Were those on your list?  People with a functioning brain, we can see the brain? Do You know YOU have a brain because other people can see it?
Then it’s not much of an observation, is it?
“but we believe we all have brains..and we take great lengths to prove to people we have a brain..”
Great Lengths?  Hardly.
“But why? who asked?”
Creationists, typically.
“Same with this question..who is it gonna satisfy to know there is no God?”
I just keep asking for any rational reason to believe in one.  Any of them.  I get bad math, bad history, poor science, Really poor analogies, and presuppositional assertions.
Not evidence.
“Would u feel good to know that when you die nobody will care about you??” 
That’s apparently what I see around me, anyway.  After long enough dead, no one will think about me, much less care.
“So if anyone can prove that there is no God..there are gonna have to go through some damn hard a*s walls to prove it..! :)”
Not really.  I mean every religion on Earth except yours thinks that yours is wrong.  And every other religion on Earth things every OTHER other religion is wrong.  The only thing you all agree on is that every religion is 99.99999% likely to be false.  So, not that hard.