If the iPhone touchscreen is not working, it might be due to several factors, such as temporary software glitches, a frozen app, a broken screen, or hardware issues. A display that is stuck or lagging may occur due to memory overload or an outdated iOS version. In most situations, the problem is resolved by turning the iPhone off and on again. Cleaning the screen or removing a damaged screen protector can also make the touch work again. The problem of the unresponsive touchscreen can be due to various things such as a temporary software crash, a frozen app, a broken screen, or hardware issues. A stuck or lagging screen might be because of memory overcrowding or an outdated iOS. Mostly, simply restarting the device will eliminate small bugs, whereas cleaning the screen or removing a faulty screen protector will bring back the responsiveness. If a problem happens frequently, it might be helpful to update the iOS or restore all of the device's settings if it's safe to do so. But if the display is physically damaged or there is some internal malfunction, then it'll probably be required to get the phone professionally repaired or have the touchscreen replaced to fix the touch function properly.