The problem is, if you type “passwd” you will only change the password of the rescue system and after a reboot your modifications will be reset.
It is required to find a way to access your real files to change the password.
This will be explained in this tutorial.
Start with mounting your partitions.
Then you will have to chroot yourself into the root partition:
sudo chroot /mnt/sda2
If you did a custom partitioning your root partition may be mounted elsewhere.
Now use the following command to reset the password:
passwd
You will be asked two times.
While you are writing, nothing will appear on the screen. This is normal and a security measure.
If you want to reset the password of a different user than root, you will have to use the following command:
passwd USERNAME
You have to replace “USERNAME” with the name of the user concerned.
When you have finished your modifications type
exit
then
sudo umountall.sh && sudo reboot
Finally click on “Boot in normal mode” in your account to reboot the server.
Your root password is now the one you have defined previously.