Let me make it simple, Win 7 Ultimate, Hardware check, builds a list of drivers to install.
I bet you never knew that windows does this, that it finds the video driver for the graphics card and from that it gives a report
and the frequency range of the monitor connected to it.
eg 1024*768 @ 60 hz, it has to build a table of refresh rates.
So you restet the bios, then what happend is likely the HD was set up in AHCI mode and the bios defaulted to IDE.
Plus it is likely as far as the keyboard and mouse they are both usb.
So on resetting the bios detect usb legacy devices on start up is turned off.
need a ps2 keyboard. It will be the case why you cannot enter the bios by pressing the delete key, F1 key, or F2.