There are a couple of ways to try and reset the password. The first thing you can try is to remove the CMOS battery and leave it out for about 20 min and then put it back in. This will clear all the settings and should clear the password too. You will most likely have to reset the system time etc in the BIOS.
Another option is to see if there is a generic password for your brand of computer that you can use to get into the settings and clear the password. Many companies use a standard password just in case something like this happens.
If you can find the motherboard manual then there might be a jumper you can short to clear the BIOS password.