Software Tool : CmosPwd 5.0
License : Freeware

You tried to access bios and you got password screen. Now, this tool helps to decrypt password stored in cmos so that you can access bios. 

Note : Using this tool is only recommended for experienced computer users. And read manual before using it to recover bios/cmos password, see the bios lists that it supports. 

(link sends you to official page of download)