My touchscreen is not responding. Do you have any suggestions on how to fix the problem?

First thing to try is a reset. Hold the sleep/wake and home buttons together until you see the Apple logo and then release. The phone should reboot. See if it works after that. Do you have a case or screen protectors on the phone?

If a reset did not work, the next two steps in user troubleshooting are restore from backup, and if necessary restore as new. If neither of those work, then make an appointment at the Genius Bar at Apple to have the hardware checked.

does a case cause this problem???

I have the same issue. My screen is sometimes not responding. I have tried EVERYTHING. Problem keeps appearing.

It is possible for a case to cause this if the screen is interfering with the touch sensor. Try removing the case and testing to see if the screen works without the case. If so, it is possible that this is causing it.

WOw... After three days of struggling with iTunes upgrades, downgrades, jailbreaks and other complicated stuff the solution was so simple! Thank you so much it works fine without the cover! Where is this censor paced? Maybe I can cut the cover a bit!

Well, the proximity sensor, which is what tells the screen to go black when you put it up to your ear is in the area around the earpiece and front facing camera. However, that should not have anything to do with the touch on the screen. If it is working now without the case, I would say there is a reason the capacitive sensor is not working through the screen. Do you have a screen saver and a case on, or just the case? If both, it could be too thick, or if just a case, it could be something about the material the screen cover is made of. You can check into other cases if you like that are designed specifically for your model of phone, and are of a quality manufacturer.

IIt is a case with a cover that you open to use the phone. Like a book. So when it is open, nothing covers the screen. I don't see how it could possibly be of any influence, but apparently it is... I will put it back on and see what happens. Thanks again!