Touchscreen won't work on IPhone?

I was reading on my IPhone 4S last night and it was working just fine. It's been physically a bit bruised and battered over the last two years (I babysit a two-year-old) but has never failed to work properly for me. Then I woke up this morning and the bottom part of the touchscreen wouldn't work! Meaning I couldn't slide to unlock, or, when I'd tried turning it off and on again, I couldn't input the passcode. From what I can tell, the only part of the screen that doesn't work is the second row of numbers down on the passcode. Unfortunately my passcode happens to use those numbers. It was literally fine last night and then I woke up this morning and it wouldn't work! What do I do?

I don't want to spend money on it because I just need it one month more and then I can upgrade to a new phone. But I need it for that one month! Please help!

Added (1). How the *** would it have been damaged it was sitting on my desk all night long nothing happened between the space of it working and it not working that's bullshit

I think your IPhone screen has been damage. I don't think there's any other temporary way to fix it rather you can change the screen if you want. If want to change the screen then you can visit the website given in the source.