Ubuntu 10.04 LTS failed to restart after upgrade

[Mizanur Khondoker]

Dear list,

I upgraded Ubuntu 9.10 Desktop to the latest LTS release. The upgrade
process went smoothly, failed to restart.
I run Ubuntu as a virtual machine using virtualbox on a Windows XP
host. After restarting, all I see is a black screen with a
non-responsive white cursor on the top left hand corner of the screen.

I did not backup anything before the upgrade -now I wonder I lost
everything on my virtual disk!.

Any help would be greatly appreciated.

Best wishes,
Mizanur Khondoker
Biostatistics Unit
Institute of Psychiatry
King's College London
Box  P020
De Crespigny Park
London SE5 8AF
United Kingdom