Ho to reset Ubuntu password (Kubuntu, Xubuntu, gOS, Mint and other Ubuntu based OSs)

What if you lost your account password?
Before you destroy your linux installation check this out:

switch on your computer, and as soon as you can, strike the Esc key on your keyboard to display GRUB menu;

highlight and select the recovery mode;

your distro will boot into a recovery shell and, after you get a console prompt, type:

user@pc:~$ passwd user

where the user is your username;

choose, enter and confirm a new password when prompted;

restart your machine:

user@pc:~$ reboot

and take a deep breath.