loose partition... loose lvm ?

Hello,

I have a problem with my LVM (on Fedora Core 3 / 64 Bits). The LVM is setup on 2 disks:
/dev/sda, with swap partition and first Lvm Partition (sda1) /dev/sdb, with partition sdb1

Yesterday, the server crashed and when it tried to reboot, it has not found the system.
Using the Fedora Rescue Disk, I get some informations:
- both partitions on sda have disappeared,
- /dev/sdb1 seems to be always here

Lvscan and other LVM informations tools can obtain the LVM parameters (uuid, volume name, size, ...)

As I'm not really confident with LVM (my LVM knowledge is very poor), I need your help ..
In your opinion, it is possible to rescover the LVM and Datas ? and how can I do ?

Thanks for your help,

Nicolas.