[CentOS] Help! Help ! i done centos upgrade

Mon Sep 13 10:30:34 UTC 2010
Ernatalo su Gmail <ernatalo at gmail.com>

Hi to all,
i have a server with Centos 5.5 - 64 bit and i done 3 maounths ago 
filesystem update from ext3 to ext4.
All things worked fine behind today.
Today i done centos upgrade and now i'heve only GRUB Prompt.

Can you help me me to strat the sterver without lose nothing?

Thanks

Ernatalo