Dell XPS 13 9315

Always had a touch screen but suddenly it is not recognised

In Tablet and PC Settings (not originally listed) "No Pen or Touch Input is available for this Display"

Not listed at all under Human Interface devices.

All Windows 11 updates are installed.

Dell troubleshooting does not identify the problem at all.

The key board and touch pad work properly.

The bottom line is that the Dell system does not recognise that there is a touch screen.

It is very inconvenient.

How do I get the Dell XPS to recognise the touch screen?