firmware password forgotten
hello as the title says i have a problem with my firmware password, i have a mac book pro 2015 13", i wanted to factory reset my mac but after rebooting there's this window that ask me for a firmware password i entered the password several time but he won't accept it, i thought i used another password so I've tried every password that i usually use but nothing, what happened ? does the password changed is self ? and how can i reset the password now ?
thank you
MacBook Pro