Re: im using lumia 535,its touch is working.
We would need more details - a Windows Central account would be useful in providing us useful information by Replying in this thread.
Have you checked if your screen (near your earpiece) is clean? Obstruction of the proximity sensor (usually by oils, precipitate and other condensate material) on the screen near the earpiece usually forces the screen to turn off during a call (since these mislead the sensor into detecting something near the screen).