Touchscreen not working

Do a hard reset first; when your phone is on, pop out the battery, and put it back again and start phone. check if problem is fixed. If not fixed, use this code *2767*3588#, note that this may erase all your data so if you can backup, then do. If problem still there, then it is hardware. take unit for servicing. you may have to replace either the touch screen or flex cable buts needs to open unit first and confirm.9look out for water damage e.t.c)
Regards