If you see Error 1962, No operating system found, Press any key to repeat boot sequence when you start your Lenovo computer, see this post.

If Dual boot menu or Choose an operating system screen is missing or not showing on a dual-boot Windows 11/10, then restore it & set a default OS by using this tip.

I have solved the "No operating system found" by replacing the boot.ini file with a known good boot.ini. Not sure if that would work with your problem.

As of Oct. 14, Windows will be ending support for Windows 10. If you don't have a Windows 11 compatible computer, there are still some options to keep access to security updates.