One of our laptops is ca 7 y/o and suddenly we can't open My Computer. If I try to open files on the Dekstop, they load, albeit very slowly. Start works, Task manager works... everything is slow, but works.
Firefox opens without any issues and browsing internet is possible without issues.
Replace the drive, install clean Windows setup on that drive, should fix the issue. An SSD is cheap now and will speed up the system overall. If you don't care how slow the system is or that the disk may fail soon, try creating a new user and see if issue is same on that other account.