hy guys,i have a problem with my backtrack

i was installed backtrack 5 r1 , everyday i always type :

apt-get update
apt-get upgrade
So my backtrack up to date.

this happen last night when i update my backtrack then restart my pc, black screen appear with error messege

boot from (hd0,1) ext3 ifc80dll-dlle-4920-97f3-cfd6060bl8f
Starting up .....

[         1-1389234] Kernel Panic -nt syncing: VFS: unable to mount root fs on unknow -block(0.0)
at this time i online using ubuntu live CD.
what i must do to fix my backtrack ? all my data is important there.(also data on virtual box)