Touch screen stopped responding

Have you tried touching the screen with a pen, or stylus. Or even your finger nail? My KORG does not work well with fingertips, needs something harder.

Using Windows?
Open up the Device Manager by right-clicking "This PC/My Computer" and select "Manage". On the left pane, click "Device Manager". Depending of the version of Windows you're running, the tablet could be listed under "Portable Devices" or "Mice and other pointing devices".
Once you see it, move that window off to the side so you can still see the entry for your tablet. Now use the tablet as normal until it stops working. If it disappears from the list, you've probably got yourself a wiring/hardware problem. (My tablet's cable eventually developed a bad USB cable from years of moving around/use).
Since the tablet itself still recognizes you after it stops responding on the screen, wondering if you may have updated the software/drivers lately (even by accident by clicking an "OK" dialog by rote...) - try "rolling back" the driver to an earlier version.
If this is really new, any chance you could use Window's Restore function to go back a snapshot or two to when it did work fine? Always back up your important files (say, documents/designs etc) to another drive before doing anything. Good Luck!

Have you tried to recalibrate the touch screen in the Set Menu? If so, and it still doesn't respond, then the touch screen might have gone bad. This is something you should have a dealer repair. About a $200.00 repair.

For the touch screen to work properly, the screen has to be absolutely clean. From the description, it is evident that the issue is confined to one particular corner of the screen, and any button appearing on that part is not responding to touch. This means that the screen is not clean at that portion. Clean the screen using a good quality micro fiber cloth. Make sure that the screen is absolutely clean and try using with a clean finger or stylus (Sony calls it Paint Pen or Touch Pen).

Does it respond to keyboard entry? If not, check to see if the "lock" icon on the screen is in the locked position. It's real easy to accidentially lock the device. If it is, just click on the lock and confirm that you want to unlock.

The next few can be a problem if the screen is not responding, so you'll need to figure out the keyboard equivalent:

You may also want to check the system settings. I believe there is a setting that will enable you to "turn off" the touch screen function.

Finally, try a touchscreen alignment in the system settings.

Use tip of Pen with ink cartridge stored. Large fingers do not work.

Best bet it to buy a new touch screen element. actually quite easy to do the change out (i have owned one of these phones). Can be found for a very low cost on sites like eBay.

Did you find a solution to this problem? I have just bought an I-Mate PDA2 and within 4 days the touch screen has stopped responding, but like your, the scroll wheel and buttons still work. I have tried the full reset and now I am left stuck on the initial set up screen. Any help would be much appreciated. Thanks

you probably have a capacitive screen, it only responds to finger press. You need a resistive screen to be able to respond to finger, nail, or pen press.