I own a Iomega 750 external zip drive. The computer reads the drive, but the drive will not rcogonize the disc. Pugged into the direct usb port. Anybody have a idea what can be wrong? The drive is 2yrs old but used twice. Tried different computers and at least three diffrent discs.

go to iomega.com or whatever your drive's manufacturer's website is and lookup your drive and download the drivers for it.