After a screen change my touch get problems [iPhone 5c]

Hi guys,

2 weeks ago i replace my screen of iphone 5c and because the screws that i removed to pull out the broken screen are damaged i decided to buy another pair. This screws are lost by post office but i haven't any problem for 2 weeks and instead from some days i lost the notification center functionality. So i removed the screen again without disassemble again entire the screen (so with the flat connectors connected i raised the screen and put it down. For 10 minutes had worked great but now if i press too much on the screen for example i have the same problem and the iphone work bad and is really annoying.

I think the problem is that the screen isn't perfectly in level because if i press with my fingers near the top of the screen this is responsive and perfect until i press but when i stop pressing if the screen isn't fitted well i have the same problem.

What can i do more than to destroy on the wall?

Thanks, Gabriele.