I had 3 hard drives in my PC. 1 SATA i believe and the other 2 were IDE hooked up. I tried to see what i had on another hard drive but i could not see it on My computer. WHY?

Then i put my original hard drive back in and now i only have my C drive showing. Please help someone

Were the other 2 drives working before?
Can you tell which drive is the working one showing up in "My Computer"?

Check device manager for the HDDs.

If only 1 is showing,check the power and cable connections for the all 3 drives.
Reboot PC and check the drives status in BIOS.
Make sure both IDE drives are probably recognized.

Hope this helps!
Bill