So I went back and changed the windows 86 back to my c: drive because the instructions I read only mentioned windows, not windows 86. Now, I get the above error and it comes up even when I try typing in the c:\windows\system32\rstui command to do a system restore.
There is no "Windows 86".
Could it be that you tripped over a spelling error when you wrote
c:\windows\system32\rstui
instead of
c:\windows\system32\rstrui
If your system is still halfway intact then it should suffice to type
rstrui.exe
If this does not work then you should tap F8 at boot time to boot the machine into Windows Repair Mode, then invoke System Restore from the menu you see there.
Note also that hacking the registry is not a good idea unless you know exactly what you're doing. Hacking the registry to change drive letter is high-risk stuff.