I would run scandisk or chkdsk...whichever flavor you have to check the drive for errors. This may possibly be enough to correct the drive unless you removed or replaced the power or IDE cable while the system was active.
please describe your physical config
(IDE Channel 0, Master, Slave \ IDE Channel 1, Master, Slave)
and which HDDs have which partitions\OS installs
type of partition (Primary, Extended, and Logical Drives, and what filesystems they are)
your data is still there, but the partition ID is probably corrupted
it maybe possible to repair it
you might have to recover the data.
lets just start at the above info
data recovery is about doing the right thing in the right order