I have no idea what to do!

No your files should be fine but you should ALWAYS have a backup of your complete system. At the very least you should be using Time Machine to backup!!

Unless the HD has crashed your data should be okay.

This means the computer has had a Kereal Panic which can be difficult to diagnose as they can be caused by either hardware or software failures. Best thing to do in your case is to take the computer to your local Apple Authorized Service Provider to be professionally diagnosed and repaired.

Yep, it’s definitely a kernel panic. Have you tried booting your Mac in safe mode? (Hold down Shift while you restart or turn on your Mac, it will take longer than normal to boot up.) If your Mac works perfectly fine in Safe Mode, then an application or malware is likely causing the issue. While you’re in Safe Mode, download and run Malwarebytes on your Mac to see if any malware is causing the kernel panics. Once Malwarebytes is done scanning your Mac, restart it normally. Are kernel panics still happening?

If kernel panics still occur in Safe Mode, you may want to bring your Mac to the nearest Apple Store or Apple Authorized Service Provider.

Try booting into the Recovery volume (boot with the Command + R keys held down). If you can then: 1 - use Disk Utility to repair the drive or, if needed: 2 - reinstall the system.