Hard drive won't open in my computer

First insure that your folder view is set to show hidden files. Then verify that there is not an autorun.inf file present in that drives root.
If there is delete it. If it returns after a restart, you have a virus. Download a good AV program, update it's definitions and scan your system.

If it is just a system hiccup then follow the next action.

For the drive; open a cmdprompt (or Run) and type - regsvr32 /i shell32.dll

I would also do a spyware check with Spybot Search and Destroy and with AdWare, both are free and can be found at sites like;
www.download.com