I have a LaCie external HD that my computer no longer recognises. Everything was fine, then I when to access some information off the drive only to be told that the drive was not formatted. I try to restore to an early date only to be told that computer could not do it. Feeling that I had no alternative I reformatted the drive. Now the drive is no longer recognise. Although the "missing" drive is a mystery, I guess the real question is what happened to start all this?

Check device mgr, start, settings, control panel, system, hardware tab, device mgr.
Look for yellow marks under drives, if any, right click on them and choose uninstall and say OK - close all windows and restart PC

Hopefully on restart, windows will install the drivesrs that are needed to recognize drive

When restart, check to see if drive is visibble now, if not go into control panel and try add new hardware to see if windows sees it

check device mgr, start, settings, control panel, system, hardware tab, device mgr.
look for yellow marks under drives, if any, right click on them and choose uninstall and say OK - close all windows and restart pc

hopefully on restart, windows will install the drivesrs that are needed to recognize drive

when restart, check to see if drive is visibble now, if not go into control panel and try add new hardware to see if windows sees it

First let me thank seahwk83 for the solution. Your description was spot on. Although my computer had some problems with the re-loading of the driver. Continuing to reload an unacceptable driver. I now have a another problem with my external drive which I will place in the correct questiion forum.