I have (only) Ubuntu 13.10 installed on my laptop and i wanted to boot from cd instead of my hdd so used gparted - I 'unclicked' the option to boot from SDV1 automatically when starting and now i can't use Ubuntu anymore. I thought it would be easy to boot from hdd again but unfortunatelly it isn't (for me). Only thing that seems to work is "ubuntu, linux 3.11.0-15-generic (rescue mode)" and "ubuntu, linux 3.11.0-15-generic", but when i tried to fix this problem by myself there is an information that the files are read-only. I would even accept having to format the whole hdd if it's the fastest/easiest possible solution. I apologise for not giving the exact output data, but i'm using not-english version of ubuntu so i have to translate to english by myself. + I guess that to solve this problem i only need to change the booting option - set it as it was before i changed it - to boot from sdv1, but i don't know how to do it.
try running from live CD https://help.ubuntu.com/community/Boot-Repair
if doesnt work. Just install again, and save your home directory in someway.