Welcome to the forum
Is the HDD even recognised in the BIOS? Or just Windows?
You don't say how old or what model your Tosh is, but on my Tosh Satellite P200D-11R it's F2 to get into the BIOS, or F12 to have a look at the Boot Menu and see if your HDD is listed there.
If the drive's not even recognised in the BIOS, I'm pretty sure any DOS-based utility wouldn't see it either?
EDIT: I've merged your two threads on the subject together - when requests for help on the same subject are split over many threads, it's hard for members to give the correct advice.
Given that there is further info in your second post, try plugging the WD drive into a USB-to-SATA (or IDE) adapter externally, and see if your PC will pick it up then. I have a USB-to-IDE/SATA adapter lying around for just this situation.