My potable harddrive isn't recognised by ...

Hi CompuG, I really hope you can help me or refer me to someone else. The thing is I have Western Digital 120GB protable hardrive which I have been using to store stuff from pc which has no more space. Yesterday I copied some files from my work pc to my harddrive and took it home. WHen I plugged it into my home pc it recognized the drive but took a long time to open any folders and then when I looked in the folders only some of the files which should have been there were. I checked the available drive space to see if they had been deleted but no change. I safely ejected the drive and unplugged-replugged it back in. This time the USB hardware install icon popped up in the bottom right menu said my device had been installed and is ready to use but no drive? It showed USB Mass Storage Device in the pop-up safely remove menu but no drive letter or drive name. On My Computer or Explorer I also couldn't find it, just my normal internal hard drives. I tried Updating the driver in Device Manager - since the drive appears as Mass Storage Device under Universal Serial Bus Controllers and as USB Device under Disk drives - but it just said that it couldn't find a better driver than the one already installed and so did nothing even though I tried updating it under both menus already mentioned. Finally I when to My Computer and clicked Manage but it didn't even appear there so I couldn't change the drive letter if that was the problem.

I'm lost and could really use some help, I have fair bit of stuff stored on the drive (it had only 7% free space left - so maybe it is fragmentation problem but if my Windows won;t recognise the drive I can't make space and defrag it) and would really prefer not to lose it. But in a worst case scenario I'd be willing to format the drive and start from scratch but I don't know how to acccess the drive to do even that. (:<)

Hoping for some help

Charrgrill