Iphone 4 screen not working

I have an iphone 4 and the screen is frozen. It doesn't let me slide to unlock or power down. After i held the top and home buttons down, it reboots and the passcode keypad appears but it wont let type any numbers to unlock the phone. Any suggestions on what i can do? I do not really want to have to restore it because im not sure if that will even work and if it doesnt i will have lost everything for nothing. I was going to back everything up onto my computer but i cant because i have to unlock the phone first.