Since this started right after something was accidentally deleted from the registry, the first thing I would try is System Restore.
From the Recovery screen, go to:
Troubleshoot > Advanced options > System Restore. Choose a restore point from before the registry change.
If there is no restore point, or System Restore fails, try: Troubleshoot > Reset this PC > Keep my files
If you are given the choice, I would use Cloud download rather than Local reinstall, since we do not know exactly what was deleted or damaged.
A reset should hopefully rebuild Windows and the registry, but there is no guarantee it will work if the recovery environment itself was also damaged.
If Reset this PC also fails, the next step would be to create a Windows 10 installation USB from another computer and reinstall Windows.
I would not start running "bootrec" or "chkdsk" commands recommended by the AI answer unless the Recovery screen is showing a specific boot, BCD, or disk-related error. Those commands do not restore registry entries that were deleted.