Many postings on the issue. This issue goes back many years.
You will see postings from 2015.
One suggestion is to connect a external monitor to the hdmi port. If it works then it is the Lenovo screen that needs repair.
Watch: LENOVO LAPTOP WHITE SCREEN PROBLEM [SOLVED]
https://www.youtube.com/watch?v=NWsy3-PBdoc
It is basically a bad connection.
The Japanese warranty dept are just getting even for WW2...
Google: Lenovo All-In-One screen turned white
https://tinyurl.com/5efdpfph
How to use System Restore on Windows 10
https://www.windowscentral.com/how-use-system-restore-windows-10
If it were the monitor why would I lose audio as well ? Last 2 times I was watching something on Youtube .