Thanks everyone for replying, I finally solved mi issue doing the following:
1.As my shadow file was corrupted by someway, I had to stop my O.S. from booting.
Quote:
Pressing stop + A repeatedly.
2. Boot from disk:
3. Executed the pwconv command, so a new shadow file could be created and also synchronized with my passwd file.
4. Changed root password
5. Had a booze and felt "Like a Boss" Meme
Thanks everyone
I appreciate your help very much