Taking out and re inserting the battery might reset BIOS in few PC's,In others find the BIOS Jumper Switch the pins turn on, it resets the BIOS setttings to factory.Then switch the jumper back,
Software procedure: when starting your pc press ctrl+M or ur boot into bios key After that press on reset Hardware procedure: take out your cell and rub it on a cloth and again put it back this is much easier.but be careful