This is pretty much the 'nuclear option', but if all else fails, you may be forced to simply erase your previous copy of Windows and simply start from scratch. Step 6. Perform a clean Windows installation. A more in-depth fix than just doing a System Restore, the Startup Repair tool (also accessible from the Advanced Startup Options screen) can sometimes fix underlying issues that may be hampering the update process. You can access the System Restore function from Safe Mode, or from the Advanced Startup Options if that doesn't work. In order to safeguard against this type of thing, Windows will usually create a restore point just before applying an update, so you can roll it back if there are any problems. After the update installs, you can restart Windows to exit Safe Mode. Accessible from the Startup Settings menu, this mode disables everything but the absolute essentials Windows needs to run, ensuring that any software conflicts that could be interfering with the update are removed. Utilise your computer’s physical power or reset button, and bear in mind you might have to hold it down for a few seconds. Resetting your PC during installation is considered to be a cardinal sin and explicitly warned against by manufacturers, but if your update is definitely stuck then you don’t have a lot of options.

Windows 7 update stuck at 99