Omran, if a hardware reset does not work, and you can not access the reset menu due to a non-functioning touch screen, I suggest to start with a Software/ OS reset. The hardware key combination can be used instead of the digitizer. This may cause some data loss.
Make sure the phone is turned off.
1. Press and hold the power key
2. Phone vibrates (release the power key)
3. Press and hold the volume down key
4. Exclamation mark is shown on the screen (release the volume down key)
Input the following key combination:
1. Volume up
2. Volume down
4. Volume down
The phone will reset and boot up automatically. This may take a few minutes.
Should this not accomplish anything, and you already tried a new digitizer, you may have a faulty touch screen IC. Attached is an image of the trouble shooting guide for the digitizer. Hope this helps, good luck.
Have you tried a reset to see if it works?
I'm having the same problem with a digitizer I got from repairsuniverse.com, Omran did you ever fix this problem? And Aristeidis, I looked up how to downgrade here http://forums.wpcentral.com/nokia-lumia-... but the software for rm-820 is not available in navifirm+ Any other ideas
I have my lumia 638 digitizer replaced, But now the touch is not working.