My computer has stopped booting up from hard drive and I can't figure this out. Please help.

Hello.

So a little while ago, I was reconnecting some speakers to the back of my computer and while I was leaning over it, I bumped the reset button on the machine while it was booting up. A stupid mistake, I know. When the machine restarted I encountered an error message that I can't recall in detail unfortunately. I believe it was along the lines that there was some sort of error caused by the incorrect shutdown and I had to reset all of my UEFI settings to default, press enter to do so.

After pressing enter, my computer will not boot. It will go past my BIOS splash screen and then there will just be a black screen with a white underscore cursor blinking in the top left hand corner. The computer will boot from a USB stick, but won't boot from either of my hard drives (one SSD and a HDD).

I have tried resinstalling my OS (Ubuntu) on both of my hard drives with no success. I then thought that the BIOS may be corrupted so I flashed it but there has been no change.

The Mobo is an Asus ASRock Extreme4. Thanks in advance for any help, if there is any more information required I'd be happy to give it.