I did something very stupid as I know very little about Ubuntu. I tried to add a rule to /etc/fstab but ended up deleting everything (and I think I saved it to). Now, when I go back and check the file I see that it's empty. I still didn't reboot, I am typing this thread from my system at this very moment. Can someone tell me how to undo the changes I made, or does someone know about a way of changing the file back? I still didn't reboot, so I think that there has to be a way of reading all my mounted partitions and add them to fstab, or am I wrong?

Can someone please reply? Thank you in advance.