My iomega ext.drive , model LPHD-UPC suddenly stopped recognized in Windows 7
I'm going to assume that you have it connected via USB.
That being said, there is information direct from Iomega found HERE .
I would also recommend try plugging it into a different computer or different USB port on this computer.
If this doesn't help, do the following:
1. Go into Device Manager (however it is you get there)
2. Expand Universal Serial Bus Adapters category
3. Right click each of the USB Root Hubs (one at a time mind you)
4. After right clicking, choose uninstall. The computer will think for a minute and it may prompt you to reboot. DO NOT reboot until you've removed all of them.
5. Once you have all of them removed, reboot the computer.
6. After the reboot, Windows should rebuild all the USB Root Hub drivers so it may take a minute. It is also best that nothing is plugged into those ports for the time being.
Once the process is finished, go ahead and try your device again.