zip drive prob wit PC

i just got my scsi zip drive and i'm using a parallel port for my pc.... everything was fine until now, but suddenly my pc will not read the disks, i cant even find the drive anymore. i dont kno wut to do. pisses me off too seeing as how i bought mpc editor yesterday, and i cant even use it now.
i kno this questions been asked before, but seriously how can i get shit back to normal...

shut down your pc, unplug the zip for like 10 seconds..........plug the zip drive up first..........always, now power up your pc and it should be fine