I have a sony vaio vgn-a290 laptop and im ...

Pull cmos cell from motherbord for 10 minutes so all settings are goes to defaults.
Also you can reset its settings with jumper settings.
You can see 1 jumper onmmotherbord near cmos cell.
Read carefully on bord you read there RESET or CLEAR bios.
it has 3 pins.set jumper in 2-3 position then power up .
Then again set to its original position 1-2.
Then all settings defaults.
Let me know if you need more assistanse.
Thanks.