I changed fstab and now Ubuntu (Precise Pangolin) does not start up. The screen goes blank and nothing happens.
I have a copy of fstab, but I don't know how to replace the current version with the backup, since the system does not star.
I've tried using the recovery mode, but when I choose "root" to go to the terminal a message specifies that the file system is in read only mode and I can't modify any files.
I've also tried mounting it again in read-write mode with:
mount -rw -o remount /
But when I do this, the terminal does not accept any other command (for every command I type, I always get the message "Denied permission").
Could you please help me fix this mess?