Backing up computer for the first time?

Ok, so my laptop is having an issue. It s a Lenovo touch screen laptop, and the screen is literally coming off. So I called Lenovo, and they said I could send it in and they d take care of everything, but I might want to back up my computer because they might have to do a factory reset or a system wipe or something. Bottom line, all my files could be erased. So I went into the control panel (I have Window 10) on this computer, and it wouldn t let me copy a system image to a 32 GB thumbdrive that I planned to use to back everything up on. However, it is allowing me to store my files, games, contacts, etc. My question is do I need to have a system image back-up of my computer? Or can I just back-up the files? My infotech teacher at school said that often times, if the computer is under warranty, which mine is, they will just send me a new one. And I really can t lose my files.

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