Disk Boot Failure. Please insert BLAH BLAH

I recently moved my hard drive to another computer in hopes that it would work (the computer). It sadly didn’t and so I moved it back to the previous computer. Now that I try to turn it on, I get the “Disk Boot Failure” error. All the plugs are in their right place. Also the Disk Drive will NOT open when I press the button. Whatare my options besides taking it to the shop and/or buying a new one?