Missing Partition

On the pc in question I had to change the hard drive which had developed a fault. The system originally was dual boot (Win2K & 98). It had an additional partition(H)which was used for data backups etc. Win2k was formatted NTFS and 98 as FAT32. Having replaced the drive with just single boot Win2k(NTFS) I attempted to recover the lost data by slaving the old drive. No problems seeing the old Win2k & 98 partitions and data was recovered ok from these areas but the old “H” partition has vanished! Much gloom because the backups are now unavailable from that partition.
Any ideas on how to recover this area?