If your Windows 10 installation is demonstrating unusual behavior such as built in apps not working or launching, you can perform a repair upgrade to fix the problem. A repair upgrade is the process of installing Windows 10 over the existing installation of Windows 10 on your hard disk, using your installation DVD or ISO file. Performing this can repair broken operating system files while preserving your personal files, settings and installed applications.
The first thing you will need to do is download the latest .ISO file available for Windows 10.
Click HERE to download official ISO media for Windows 10 from Microsoft.
Starting the installation
When you download the .ISO file, you can start the upgrade immediately by simply double clicking the .ISO file to mount it. If you are running Windows 8/8.1 and plan to upgrade your operating system, you can also use this method. Windows 7 and earlier will need to prepare install media. If you prefer to prepare installation media and start the installation from that, review the following article (see section Download and prepare .ISO file):