How to Edit the Registry When You Can't Log In
- 1). Restart your Microsoft Windows computer.
- 2). Press "F8" as your Windows computer is restarting. The Windows "Boot" menu will load. Select "Safe Mode" from the list of options now on your monitor and hit "Enter." This will boot Windows into Safe Mode. You will see the Safe Mode desktop in just a couple of seconds.
- 3). Click "Start."
- 4). Type "Regedit" (minus quotes) into the "Search" box. Click the icon for "Regedit" to open the Microsoft Windows Registry Editor. You can use the native "Regedit" tool to make any registry edits you need while logged into Safe Mode.
Source...