Fsck

Fsck is the Linux filesystem checker. Generally ran during the startup procedure, or periodically to check for small inconsistencies in the filesystem. The command varies, since it needs to be created dependent on the filesystem, not the system itself. Fsck can fix many different problems automatically, but usually prompts what to do if something unknown comes up.

Usage
fsck /dev/sda1
 * Replace /dev/sda1 with the location of your drive