Hello to everybody

After a normal reboot, the NAS does not see the 2 hard disk
I tried to insert one of the two hard drives in a PC (Windows 7 + ext2/3 drivers) the OS sees the partition but can not read it

The discs are not damaged and my data (I hope) still in

How can I mount again the disks in the Valkyrie or recover the data with a PC

Is very important for me (lots of important data)
I always thought that with a RAID system my data would be pretty safe but actually I cant' get them back even if no disk problems occurred!!

Thanks in advance for your help,