How to restore a Gateway SX series desktop to factory defaults

Hello,

I have a Gateway SX2110G-UW308 Desktop computer with Windows8.1 on it. My problem is that I can't log into it anymore, Every time I try it flashes on and off three times and goes back to the login screen. I also can't access boot menu because it is set to quick start. Can someone please explain how I can fix this problem, because it didn't come with an OS disc and I also don't have a Recovery disc for it. I've tried using the F1, F2, F8, and even the F10 buttons as mentioned in other posts but those don't seem to do anything. Can someone please help? I need to get my computer working again and I can't afford a new OS disc or a new computer.