scroll down to the creation tool download. you will also need to download the ISO file for your version of windows, the tool use's this to update and replace as needed an corrupt files it finds while keeping all programs and settings.
If your using an older version of windows, you'll need to use what ever process available for that OS to fix it.
Buying a new computer probably would be easiest if you have the cash.
if it never used to crash, then upgrading the gfx diver may help, or downgrading it if already up to date, also run as low res as possible, like 1280x720 at most, and try disabling your antivirus temporarily while offline.