The boot Devices have been changed. BBS boot priority will be affected ???

Earlier i entered into setup when booting up my computer. i changed the priority of drives which boot up with HD first, CD second, and Floppy third and then exited. Next time i boot up my computer i get the message above. it also tells me to go into setup. i do that and try to change back the settings to default but i can't make any changes to anything. how can i restore my PC back to default BIOS and boot up settings????