Windows turned drive F: into drive G:, so the PC's owner asked the Answer Line forum how to change it back.
Windows allows you to manually reassign drive letters, and that's your best solution.
Click Start, right-click My Computer (just Computer in Vista) and select Manage to bring up the Computer Management application.
In the window's left pane, beneath the Storage heading, select Disk Management.
Now wait as Windows figures out what drives you have and brings up a map.
Once the map is up, right-click the drive you want to change and select Change Drive Letter and Paths.
This will bring up the Change Drive Letter and Paths... dialog box. Click Change.
Select a drive letter from the pull-down menu on the right side of the resulting dialog box, then click OK.
If you're prompted to restart the computer, do so. If not, don't worry about it.
My thanks to forum regular Mphenterprises for answering the question in the original forum discussion.