I fixed our neighbor's laptop the other day, and I plugged my USB hard drive into it to transfer some files. After I plugged the drive back into my own computer, Windows 7 suddenly couldn't access the disk (notice the drive space indicator disappeared in the first screenshot, below.
No amount of fiddling with the security/permissions/owner would bring it back, either.
This fix is to use the "icalcs" tool to reset the drive's permissions. To do so, follow these steps:Launch the Command Prompt as an administrator (Start > Search for "cmd" > Right-click on "cmd.exe" and select "Run as Administrator")
- Switch to your drive that is having problems (replace H: with your drive letter): CD /D H:
- Type: icacls * /T /Q /C /RESET
- Wait for a while. Mine took about 10-15 minutes.
When it's done, you should be able to access the drive as normal.