need hard drive help asap

Just unplugged my hard drive to try and get an old hard drive working as slave
however when i plugged it all back in my pc no longer detects my hard drive either of them.
comes up the boot disk error please enter blah blah

anyone got any idea why my pc has certainly decided not to see my hard drive?

 

Are they detected in the bios?

put in the windows cd... go to repair and run chkdsk. presuming ur using windows.

 

nope what i meant by not being seen by pc, they are not seen by the bios

 

problem fixesd was a faulty ide cable something i should of checked first