Why my touch screen is not working?
Display is working well, but touch screen is not working. With other module it works well. Is it possible to repair the touch screen only, not changing the all module?
The touch screen (digitizer) is fused with the LCD together. Since that does not work you will need to replace it with a whole new screen.
Not really sure as to why the touch screen would not be working. Number of possibilities: liquid damage, screen display has too much damage, digitizer / touch screen got damaged after crack.
Clients that come to me for S4 screen repairs they usually either have a no display as in dead LCD or glass is cracked but touch screen and LCD display is working.
There's a ribbon that goes from the touchscreen/digitizer over the top of the lcd screen and slips into a connector clip. Really small!! This might have become lose,or actually broken. Also at the top of the lcd screen there's 3 little solder connectors ( ÷ and - ) if these solder become loose it will also prevent the screen from being responsive to the touch but display will work fine.
Hope this helps