My System and HDD Password is not working

I have a big problem with my PC. One day my computer for some reason wasn’t asking for my PIN number and was only asking for my password I barely remembered putting on a password so I looked online and it was until I got to my UEFI Bios settings where I really up I set up a system and HHD password which I DEFINITELY know that password to but it’s not letting me log in, I don’t know if it’s because I did change it or that it just doesn’t want to work I am afraid that I won’t be able to fix it. There is also a service tag and I want to know where I can go to use that for help or something please respond to me when ever you get the chance to please!! I would also like to know how to get rid of it because I do t want to use it again if it was to do the same thing again.