What happens if I factory reset my computer?

That is called a Clean Install of the Operating System.
You loose eveything unless you back up to an external hard drive.
All Programs will have to be reinstalled.
All Drivers will have to be reinstalled.

Don't forget to go into your Web browser's settings and retrieve any UserIDs and Passwords that you might have saved in your Web browser.

Don't forget to back up everything that you want to keep: documents, images, music files, video files, etc.

After you have performed the "factory reset", you will need to download and install all of the Windows updates that have been released since your computer was sold. You will need to fetch the installers and install any third-party software that you might have acquired and installed since you first turned on your computer.

Everything gets deleted you will have to re install all software