Your USB recovery drive can still help you troubleshoot and solve these problems. There has been a recovery image file on your computer, but it in addition to occupying space on your disk, there may accidentally deleted or installation of the system has been formatted off. In order to save the space, you can remove the restored image from the computer, and use your U disk drive. Thankfully, Microsoft is aware of the problem, and it has developed a very simple way to reinstall the system to help you get back everything you have lost.

Note that, according to the official document, if you use the Win7 system, you will need to enter a Win8.1 product key to make this process work smoothly. And the tool for the U disk or disc for the 32 bit system has at least 1.8GB of available space, the 64 bit system has at least 2.3GB available space.

1 run Win8.1 setup.

2 system when you run or save the file, select "run"".

3 system prompts you to enter a product key, enter the 25 digit product key.

4 when the system prompts you to install Windows 8.1, select "Install" by creating the media, and then click next ".

5 select the media type you want to use: U disk or DVD, click next to continue to install.