I try using the front camera but doesn't work at all?

I got my phone around march 25.It's an iPhone 4S, black, it has a very small crack on the top right corner and the camera acts funny. The first few das the camera was okay hit then starts gettig a bunch of lines everywhere. A few days later it won't wen open. Until this day it still doesn't work. I tried everything I possibly can. How can I get the camera workin again? (Btw my back camera works fine. So does the flash)

Since there's a crack in the corner, it could have snapped the ribbon cable that connects the front-facing camera to the iPhone's motherboard, causing all this mischief.

Unfortunately, the only way to fix this would be to buy a new phone, or get the entire display replaced, which can be quite costly.