Soft reset your iPhone 8

Unless your problem is caused by physical damage, there's a good chance you'll be able to solve your touchscreen problem by simply restarting your device. Follow these steps to do so:

1. When the slider appears, press and hold the Top (or Side) button.
2. To turn your gadget entirely off, drag the slider.
3. Press and hold the Top (or Side) button until you see the Apple logo after the iPhone has turned off.

If restarting your iPhone 8 does not work, simply push and release the Volume Up button fast. Then, swiftly push and release the Volume Down button. Then hold down the Side button until the Apple logo appears.

Uninstall apps

If your touchscreen stops working after you install an app, try removing it to see if it fixes the problem. Apps that are incompatible or badly developed might cause the operating system to malfunction, resulting in a slew of problems. To uninstall an app, follow these steps:

1. Touch and hold the app lightly until it jiggles.
2. In the app's upper-left corner, tap.
3. Select Delete.

see if these solutions work or not