In the OVH Manager, select your VPS from the Infrastructures list. From there, on the right-hand side of the page, you can click on the "Reset the password" button.
Once your VPS has rebooted, an email containing a temporary password will be sent to you.
Connect to your VPS via SSH using the temporary password that was sent to you.
On the command line interface, enter the following:
$ fdisk -l
This will list the partitions on your HDD, and the partition where the password is will be highlighted with an asterisk ( * ). It should look something like /dev/vdb1 * or /dev/sdb1 *
From this point on, I will use /dev/sdb1 as an example, but depending on your output in the previous step, you may have to use /dev/vdb1
Run the following command:
$ mount /dev/sdb1 /mnt
(You may get a message that it is already mounted)
$ chroot /mnt
Finally, generate your own root password with:
Once all of this is done, restart your VPS in normal mode from the control panel and you will then be able to connect using your new password.