Unable to boot

I began receiving no boot device found error messages upon startup.

I updated my bios and changed the boot mode options from legacy to uefi as suggested by Dell.

It was also suggested to reload my OS.

I cannot get my system to reboot at all. I am only getting a black blank screen.

I have tried both the F2 and F12 commands while trying to reboot but without success.

What other options do I have?