Took off front screen to iphone 4s wrong?

Went to change the battery on the iphone 4s but I took off the front screen like I would on a 5c (popping it off with a suction cup). I now realise I should not have done that and so I put it back on but now it comes off easily and does not work. When I turn it on the screen behind the glass lights up and it vibrates but the actual front screen does not respond at all. It comes off completely so I'm not sure if I've torn something or what but it doesn't work.

You took the totally wrong aproach. If you want to change the battery, you have to unscrew to bottom to screws, that will take the back screen off. But its too late for that. I'm pretty sure you are in trouble and its not gonna work again

You need a new screen assembly.

With the 4, it's the very last thing to detach from the outer frame - it dismantles from the back, working forwards.
(I've not done a 4S).

The screen kits are relatively cheap on ebay.