Hi,
Upon re-boot I logged on as root and looked at Gparted to find my whole disc is now un-allocated space.
Please clarify the context: your rebooted from liveCD ? (look like yes, but just to be sure ...)
Apparently your partition table is lost, if I remember correctly there should exist some utility to recover lost partition table,
right now I don't remember where I have seen such rescue-utility, may be SystemrescueCD ? .
Do you have any backup ?
Before to try any other install/restore operation, try to search for some partition rescue utility ...
Good Luck
AS