Partition unreadable after resize PPM9SE

I resized two partitions on the same physical drive and now cannot boot from or mount/read the shrunk partition. I used the Resize wizard and accepted the recommended parameters. The resize proceeded to completion (2hrs) but on rebooting I got a "Kernel panic - not syncing:VFS:unable to mount root FS on unknown block (0,0)". (Ubuntu Linux).
PPM can see the partitions and reports their correct sizes as can my Linux rescue CD but cannot mount it. The other, now larger, partition mounts and is readable.
I dual boot with XP (on another physical drive) and that still works fine.
I have successfully performed this operation (resize) previously but maybe not on my Ubuntu boot partition. Grub comes up as normal.
I'm sure all my files are still there but it seems there is some basic address location missing.
How can I get it going again?

 

Did you try to perform recovery from Linux installation CD?
Or to re-init GRUB from the installation CD?
The issue could be related to the changed system Linux partition start. GRUB boot loader refers to wrong sectors I suppose.

 

If only it was that easy.
I have been able to open both partitions with various tools and backup one of them. complete with errors, the other gets to 90 or so Gig then fails.
Most of the files are readable but about 10-20% of them at random show their size as 93,241,741,824, they're all the same size and mainly less than 1Mb!
I think all my data is there but whatever Linux uses as a FAT has some systematic errors in it.
Ironicaly I was trying to enlarge a partition because it had filled up with backups. I think I can recover a lot but something to fix the filesystem would save days of searching and trying.
My other drive has a cranky old XP system on it so I still have reasonable functionality.