INACCESSIBLE BOOT DEVICE on RAID5 NT SVR

I received the above message on my server. I have not changed any hardware or software. Using the LAST GOOD did not work-same message. I ran the hardware diagnostics but found nothing wrong. I tried to repair using the NT CD-ROM but it could not seethe hard drive. Bootabel floopy gives same message and I can not get to the hard drive to change any fiels. Any suggestions?