The first thing you want to do when your Explorer.exe stops working is use sfc /scannow. Load into Windows and get to the point where you have no explorer.exe. Hit CTRL+Shift+ESC to bring up task manager. Start a new task: msconfig. Use this to select a diagnostic startup and reboot. If you have exporer.exe at this point, type cmd into the search bar and right click cmd and run as an admistrator. After that, run sfc /scannow.
If you have no explorer.exe/UI in diagnostic mode, then try safe mode. SFC should work in safe mode. You must use an elevated cmd for some commands even if you are the only user.
Inside the administrator elevated cmd, I would also run chkdsk C: /f to check the hard drive for issues. This scan may take a while and cannot be safely interrupted.