|"It was there in the first place, I never changed any settings, nothing...."|
OK, then you chose to buy a computer with RAID 0. Did you know what you were getting when you bought it? I'm guessing you didn't. RAID 0 is approx 1/2 a reliable as a single HDD, or to put it another way, it's twice as likely to fail. You should have had a backup plan in place.
I don't know the conditions of your drives, but if you reboot, you may never get back into Windows again. If you have any photos, videos, word docs, etc that you need, get them copied off while you still can. Other than that, you will have to determine which HDD is bad, then remove it from the system. Run a diagnostic on the remaining drive. If it checks out, reinstall Windows on the single HDD.