Why has my touchscreen stopped responding properly?
Most touchscreen faults are not the screen failing — they are interference with how capacitive sensing works, and the causes are distinguishable by the pattern of the fault.
How the screen senses touch. A grid of transparent conductors maintains a small electrostatic field. A finger, being conductive and largely water, disturbs that field at a point, and the controller calculates where. It is detecting conductivity, not pressure — which explains almost every failure mode below.
The common causes:
Moisture. Water on the screen is conductive and registers as touches. Symptoms are erratic phantom presses, keyboard letters typing themselves, and the screen appearing possessed. Dry it thoroughly.
A screen protector, particularly a thick, poorly fitted, or bubbled one. Air gaps and cheap material reduce sensitivity, usually worst at the edges.
Grease, sunscreen or hand cream, which insulate.
Gloves, plasters or very dry skin, all of which reduce conductivity.
Charging with a poor-quality or faulty charger. This is a genuinely underrecognised cause: electrical noise from a cheap charger interferes with the sensing grid. If the screen misbehaves only while charging, that is the diagnosis, and a different charger fixes it.
A software freeze, where the whole device has stopped responding rather than the screen specifically.
Physical damage, including drops that damaged the digitiser without cracking the glass, and internal moisture ingress.
Extreme temperature, which causes temporary unresponsiveness at both ends.
How to diagnose it:
Is it the whole screen or one region? A dead strip suggests hardware; whole-screen suggests software or interference.
Does it happen only while charging? Charger.
Force restart the device, which distinguishes a frozen system from a screen fault — the method varies by model.
Remove the case and screen protector and retest.
Try safe mode on Android, which disables third-party apps — if touch works there, an app is responsible.
Check for a calibration or touch sensitivity setting, which some devices offer for use with protectors.