If you've nothing valuable on the Ubuntu install (and you can't access it or haven't for several months, so that seems a reasonable statement)why don't you just do a reinstall? If you have vital data, you could move it using the Live CD then put it back whan finished.
I like the look of EDDY1's solution though, I need to recover a system I've just put CENTOS 5 on so I can pick up my Ubuntu 10.10 and Fdora 15 partitions. Cheers! ED.