i have moved you to hard drives
check the cable to drive has not come loose
to reinstall when it asks if you wish to load a 3rd party driver select yes and pop the floppy with the sata driver in
without it it will not find the drive
if pushing the cable back in gets you into windows run
chkdsk /r
then to check for infections follow the 5 steps
http://www.techsupportforum.com/showthread.php?t=15968