Yesterday my touch screen stopped working completely , after restarting my mobile it worked .
But the lower half works and upper half doesnt respond.
Means if the touch the upper portion the lower portion responds .
I tried *#7370# and reinstalling the firmware 7.48 but no use.
Please take your device to the authorized Nokia Care Centre in your area as there is nothing more that can be done by at this stage.
Could you try to go to settings and calibrate your touch screen again. I hope it will help you.