Can iPhone hardware defects affect performance of some apps?

I recently have had to get an iPhone 4 repaired. My LCD screen was not lighting up and not even a system restore could change that. I took it to a center and while they did manage to fix it, now I'm having trouble with some apps, namely Twitter and Facebook. Just those two go into like a small-screen glitch when I try to load them. My assistive touch doesn't work anymore either; it just sits in the center of the screen, unresponsive.

I understand this problem isn't very common, so if you know of anything I could do to get everything functional again, I could use the help.

This may be a reason.