Windows 10 won't start after attempting Windows update January 2022

Windows 10 started updating but got stuck at 90%. I left the iMac (catalina) on all night but the next morning it was still at 90%.
I rebooted MacOs (perhaps I shouldn't have!) but when I now try to open Windows 10 only the Parallels Control Center opens.
When I tick on Windows 10, it shows busy at first but nothing else happens, no error message.
What should I do now?

 

Hello, Click on your Windows 10 virtual machine. After opening the virtual machine, you will see the "actions" option appear on the Mac menu bar where the Apple icon appears on the Mac side. Now click Action > Click Stop > Do not click Shut Down, as Shut Down is different from Stop. Now check if everything is working fine by opening the virtual machine again. Please follow this link: https://kb.parallels.com/123111 to learn more about Stop. Thanks.