I have been using Zorin and I have a display contrast problem when waking up from sleep. I posted a request for help on the Zorin forums and someone suggested I edit grub...

I followed their suggestion but the result that the screen display is completely broken and I cannot get back to terminal to reverse the change I made. If I boot and hiot escape I cqn ghet to the grub menue but I can't seem to get to terminal from there.

I have posted some screen shots there on this link:-


I would be grateful of any suggestions on how to fix without having to completely re-install.