Today, I got the following error while booting up my Ubuntu 15.10 Desktop.
ext4-fs error ext4_lookup deleted inode referenced
It doesn't boot up and kept showing me the above error continuously. After a couple Google searches, I found the solution for the above error is so obvious. Yes, I suppose the file system EXT4 for the partition /dev/sda1 is corrupted. So, I decided to log in to the single user mode and perform manual file system check.
To log in to the single user mode, reboot your system and select Advanced options for Ubuntu from the GRUB boot menu.
Check the following screenshot.
Then, select Recovery mode.
On latest Ubuntu versions, you can log in to the single user mode as described in the following link.
At the single user mode prompt, run:
You'll be now asked to answer a couple of questions. Type "Y" until you get the problem solved.
Finally, you'll see the FILE SYSTEM WAS MODIFIED message. Type reboot and press ENTER.
That's it. Now, the system will boot up without any problem. Be mindful that some of your files might be lost already. If you have anything important on your hard drive, connect your hard drive as secondary hdd in any system and do the backup before running the fsck command. Also note that this method will not work if your hard drive is already dead or nearly in dead condition. Keeping an external backup is always a recommended.