It sounds as though your computer has the wrong time in the CMOS. The CMOS (Complementary Metal-Oxide Semiconductors) is the chip that holds the basic startup information for the BIOS, system and its peripherals while the system is turned on and off.
If you can get into the BIOS check the date and time settings and make sure they are correct.
It may also be a case of the CMOS battery going out. When this happens your computer will tend to not keep the correct time. They are cheap and relatively easy to replace. Before buying a new batter your can try to take it out and let it sit for about 15 minutes or so to reset the CMOS and then go put the battery back in and go into the BIOS and reset the clock.
Hopefully taking the batter out or replacing it will get past your lock icon asking for the password. If not then you may have to find out the manufactures of your computer's motherboard to see if there is a common password to get past the lockout. If it's a laptop then it should be easier to find this code based on the manufacturer. Just search for CMOS or BIOS default password for your brand of laptop.