Error- D:\ is not accessible. Access is denied

All of the sudden the D drive gives me an error when I try to open it:

D:\ is not accessible. Access is denied.

I have files on the drive that I would like to recover, so I do not want to reformat the drive. It acts almost like the computer doesn't recognize the drive. I have a feeling it's something with security settings, I may have accidentally changed something on the drive.

I'm running on a Acer Aspire laptop on Windows Vista, SP2. I beleive both the C and the D drive run off of the same disk drive. At least that's all the Device Manager shows. So correct me if I'm wrong, but that would make it a partitioned drive.

Try right clicking on the D: and go to Properties. Click on the security tab and add the user EVERYONE to the list of Group or User Names. Give EVERYONE full control in the little box below. See if this will get you access to the drive. It sounds like you have changed users and/or physical computers (hence switching users again.)

Click Start Button and type "diskmgmt.msc"
Right-click the "diskmgmt" and select "Run as Administrator"
Select the D: drive and right-click it.
Select "Change Drive Letter and Paths"
Click "Change"
Select the drive from the list of drives on the top-right corner and click OK

Make sure that the drive you want to change is not in use. I hope this helps, please let me know... It worked for me just 20 minutes ago and I access my D:\ once again :) It has accurately helped me