Windows may be the most popular operating system but there are alternatives. The Macintosh operating system is also popular but it is proprietary and like Windows it is not free. Linux is a free and open source operating system that can be used together with or in lieu of the other more popular operating systems.
In the unfortunate event that your operating system gets corrupt you may risk losing all your data by reformatting the hard drive. Your data may be saved, however, if you can boot into your operating system using a bootable version of Linux saved on a USB drive.
Instead of booting into your standard operating system you install Ubuntu onto your USB drive and boot from the USB drive at startup. This may require changing the boot order in your computers BIOS. You can do this by pressing the appropriate BIOS setup keys shown when your computer is starting up.
Once you ave booted into Linux you can either install the operating system on a different partition or use it from the USB drive. Be very careful if installing Linux to ensure that you do not inadvertently overwrite existing files by formatting the a hard drive if you do not want its contents erased.