The most succesful tool I have used for recovering 'lost' partitions is Acronis Recovery Expert. Go to acronis.co.uk and you will see that they have trial versions for download - the full product is only £22.50
Incidentally, if you are running XP, try unplugging the slave drive, power off, power on, and close down again. Then re-connectthe drive, power up, right-click My Computer, choose Manage, go to Disk Management - if your slave drive is listed, right-click it and mount it. It has worked for me before on a couple of systems.