If i opened my iPhone and damaged something will apple still help me fix it iPhone 4S

So long as you put it back together they will let you do an out-of-warranty replacement for $199 USD.

You would have to ask Apple:

"Certain damage is ineligible for out-of-warranty service, including catastrophic damage, such as the device separating into multiple pieces, and inoperability caused by unauthorized modifications."

"Apple reserves the right to determine whether or not your iPhone is eligible for Out-of-Warranty service"

http://support.apple.com/kb/index?page=servicefaq&geo=United_States&product=ipho ne

Maybe.  You'll have to take it in and ask. You may be denied a discounted out of warrany replacement since it was opened by an unauthorized person.

If you take it in to them with the "replacement" screen installed, they will almost certainly turn you away. There is no such thing as a legitimate source for parts for an iPhone. Apple does not sell parts.