Try unplugging it, waiting 5 minutes and plugging it back in. It's referred to as power cycling.

It might be something as simple as the power supply dying.

thankfully, it was just a problem with the computer not trying to boot from the hard drive and instead trying to boot from my tablet installation disc... haha... woops

Woo, alright, troubleshooting time! Good news is, your actual hardware is fine. If it physically powers on and shows the HP screen followed by the flashing underscore, your stuff is good. Now, that blinking underscore is what happens when the computer searches for boot media, such as Windows on your hard drive. Did it hang up on that blink, or say something like "Boot media not detected" afterwards?

It hung up on that blinking infinitely, so someone suggested that I go and see if my hard drive was the media it was trying to boot from- and it wasn't!
after changing that to my main boot device, it fixed the problem (THANK GOODNESS)

get a laptop, backup hard drives, reinstall windows (F9 or something?), funfunfun

Got a Windows Recovery Disk?

If Windows is still installed on your harddrive, your BCD might be corrupted. If you have a recovery disk (USB/DVD), then you can go in Recovery Console and enter in a few commands to repair your BCD. I can help ya get the ball rolling

I actually don't have one, but I was able to get the computer working again so that's gonna be the next thing I do for the future haha, who knows when this thing is gonna crap out on me again

If it's just a flashing cursor, try unplugging all USB devices and see if it boots.
If not, check the BIOS and ensure your HDD is detected and set to the main boot device

that actually ended up being the problem, thank you so much! ;w;

I've had this same exact problem many times. Glad it fixed it :3

Frin. Cmon. Lmao

glad yer back onboard Chief :D