need help on a win2k issue ...

i just installed another 80gig maxtor ( NTFS). i then then
put 5 hours of EDITED video files onto it to use as backup.
when finished i went thru the new drive to make sure the
video files played back. one of the files would NOT play so
i went to the original AVI file on another 80 gig to see if
it was OK . it did play back but then locked up win2K.
after 10 min of control/alt/delete the computer shut down
and restarted. as it was booting UP a message came on
saying something about NTFS needed to check the intregrity
of the sytem files on the 2 drives. ALL files on BOTH drive
are GONE?( i can't explore the drives) both drives show up
BUT when i click on em it says DISK structure corrupted on
BOTH drives???? it appears that both drives need to be
formatted ... THIS can't be !! these were edited video
files 30 hours cut down to 5 hours !! the new drive was to
store these AVI files as backup and now the original and
backups have vanished.

any suggestions on how to get win2k to see em ?? or why
this happened or how to avoid in future ??