I have a single operating system (Ubuntu). When I start my computer, I get a black screen, and after a few seconds, the Ubuntu loading screen, and after that I'm able to use my computer as usual. I do not get the BIOS loading screen. I've tried F2 and F12 (which are the keys used in Toshiba Satellite, my laptop) while the black screen shows to enter BIOS setup, but those don't work.
How do I fix this? I've already reinstalled Ubuntu (not because of this) and the problem still persists, though I doubt that Ubuntu is the problem.
EDIT: My questions is not how to enter the BIOS setup - I know how to do that. The problem is that I don't even get the usual loading screen that says "TOSHIBA" and "Press F12 to enter setup". My computer, on being turned on, directly shows the Ubuntu loading screen