In more detail,
All you have to do is clear or "flash" your CMOS. Most motherboards have a 3 pin "jumper" that can do this. All you have to do is...
1. Make sure the power is off on your computer.
2. Remove the screws from the outside of your computer, and open the case of the computer.
3. Take a small flashlight and look all over the board... there should be several small sets of pins (in addition to many different transistors,etc....) set in different places on the board. Some of the pins will have at least one small "jumper" which is just a small piece of metal encased in plastic which will connect 2 pins together.
3. Look for a set of 3 pins that has one jumper connecting two of the pins. Around this set of pins it should say (in VERY small letters) "cmos". If the pins are not labeled "cmos" keep looking till you find the one that is labeled. If there isn't one that is labeled, you have to look in your motherboard manual to find which one is the cmos set of pins.
4. Remove the jumper from the set of pins it is on originally (pins 1 and 2 usually) and set it one pin down (pins 2 and 3 usually). Leave it on here for a couple of seconds or a minute or so...
5. Remove the jumper from pins 2 and 3 and put it back onto pins 1 and 2.
6. Put your computer back together and start it up. When you start it up, you should get a "CMOS-Checksum Error". This should either load all the defaults for the motherboard, or you can then press "Delete" during start up and edit the default bios settings to your liking.
Good luck, it's fairly simple. Do a search for Discharging CMOS, or resetting the bios on the internet, and you should get some additional guides/info.
Also, check your motherboard manufacturer for information if it's available.