This time there is no repair mode. So I need to make a repair mode usb stick first. I found that C:\Recovery was emputy... Then I followed the steps on the page: http://www.digitalcitizen.life/create-usb-memory-stick-system-recovery-tools From the usb stick the repair mode was established.

The PC was HP and it has a couple of partitions: C Drive named System, D named OS, E named recovery. I found necessary files from C and D, and copied on USB stick. It booted and ran into repair mode. I did the same thing as the 1st way.

But somehow I can not find the file sethc.exe nor cmd.exe... I rebooted the machine to check they exist or not. I found they surely exist.

An idea comes up into my mind. If the sethc.exe and cmd.exe file manipulation is the key, then we don't need to use the repair mode, but rather linux system and mount the partition and do the manipulation.

That is the 3rd way.

Conclusion: I don't know this way works or not 100%. But it should work.