Turn off the computer and unplug the electricity. Put the computer case flat on the desk. Open the computer case. Touch the OUTSIDE edge of the metal part of the case. This will prevent any static electricity from damaging parts.
Now, on the motherboard there is a battery that looks like a battery that you find in a wrist watch. There is usually a tab that holds it in....if so, move the tab with your fingers to release the battery. If not, you may need a screwdriver to pop it out. After taking it out for 10 seconds, put it back in, + side up.
Then put the cover back on your case. Set your computer back up. Plug power in. Turn on your computer. Your BIOS should say something about it being defaulted, or reset.
If this fixes the computer problem. Then enter your BIOS by hitting the F1, or maybe Esc key. Set your settings like Time and Date, hard drives, etc.
Set the CD drive to boot first in the boot order of devices in the BIOS.
When done, hit the Esc key and save the changes.
Put your operating system on the computer.
Enjoy your computer.