Hi, I am Dave, I will help you with this.
1
Boot your PC into BIOS, find the option to restore BIOS defaults and apply that, then check the boot priority list to ensure either your system drive or 'Windows Boot Manager' is set as the default device, save those settings and restart your PC to see if Windows then starts up normally.
2
If not, did anything happen on your PC before you could no longer start your PC?