External Hard Drive Problem

I am using a Glyph external hard drive on my XP PC and it seems to have developed a recognition problem. When I plug it in, XP goes far enough to see that it is mounted and provides the "safe disconnect" icon, but the disk no longer shows up on My Computer so I cannot access it. There are no vital data on the disk now so I would be happy to reformat it and begin again, but I can't get at it. Device Manager tells me that the disk is functioning correctly, but I still can't see it. Has anybody got a way?

Thanks

 

i just posted this earlier, it applies to xp. i'd try this and go from there (let us know what happens). g/l, sos

http://forums.majorgeeks.com/showthread.php?t=154700 <-- External Hard Drive

 

It does show up under Computer Management>Disk Management and, interesting, it shows up cross-hatched with no letter assigned and with the description "Healthy (GPT Protective Partition)". I don't know what I did but any idea how I undo it?