You might have a situation in which you need to run an FSCK in your server and you do not have a root password or you do not get the desired login prompt due to any disk issues, which might need an FSCK.
You can try the following steps to attempt an FSCK :
* Reboot
* Edit the grub
Edit grub entry by pressing ‘e’
Edit the kernel line by pressing ‘e’
Add the following at the end of the kernel line: init=/bin/bash
Press enter to save and ‘b’ to boot
The above given statement boots straight into a shell without any password. You can now manually run the FSCK using commands such as : fsck -y /