Omg. Just take the computer back from him and make these changes in the Registry yourself. I mean, he doesn't know what he's doing if he doesn't know how to fix it. This is pretty basic, if you ask me. This literally takes about 5 minutes to do! The only reason why I asked you in the way that I did is, some people are EXTREMELY afraid of making changes to their Registry. However, he doesn't know what he's doing, so tell him that you want your computer back now because you have been told how to fix it and you'll just do it yourself. If he protests, then make him do this - however, it would be a million times easier if you just did it yourself. I would bet though that he'd be like, "umm.... I don't think you should do this", and that's because he doesn't know what he's doing.
So, let's get started!
First, open the Registry editor, called "Registry Editor". Or, "regedit.exe". My preferred way to open it is by opening the Start Menu and then typing either "registry editor" or "regedit" and then pressing Enter as soon as it is selected for me in the Start Menu.
Now, with Registry Editor open, go to these keys one at a time (don't open them all at once because then it becomes overwhelming):
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders
HKEY_USERS\S-1-5-21-123456789-1234567890-123456789-1000\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders
With these last two keys, where you see "123456789" and "1234567890", you will find your own unique user ID. For security reasons, this number should never be shared with anyone. That's why I replaced mine here with just "123456789" and "1234567890".
Anyway, in each of these 4 keys, you will see what you need to change in the right-hand pane because you'll see all of the occurrences of "A:\folder name". So, all you have to do is change each one to be exactly what you want it to be (double-click each one in the right-hand pane, or just right-click and choose "Modify").
After changing these in all 4 of these keys, close Registry Editor and reboot. You might also be able to get the changes to take effect by simply logging out of Windows and logging back in, but I'd rather reboot just in case you'd end up finding that you had to reboot anyway for these changes to take effect. Usually though, changes in the Registry will take effect when simply logging out and then back in.
After you do this, everything will be fine.
Edited by TwoCables - 4/26/15 at 2:59pm