Whenever we have a problem, there are two possibilities of problems - hardware & software.
- SOFTWARE PROBLEM Open device manager & navigate to the driver related to touch screen.
Then first try troubleshooting the driver.
Then update driver and try using your touch screen once.
This should be able to fix it, if doesn't then please try to roll back the driver.
Next is to run sfc /scannow command. Simply type 'sfc /scannow' in search and execute this command as Admin. - HARDWARE PROBLEM
We can do nothing by ourselves for a hardware problem. Please take the laptop to Lenovo service center for possible repairs.