Pls pls HELP ME OUT. My little (18yrs) brother has change my adminstrative password and user account. How can?

HE CHANGE MY PASSWORD AND ADMISTRATOR PASSWORD USING F8, START WITH NETWORKING, AND SAFE MODE. NOW I HAVE BEING TRYING TO CHANGE IT BUT IT WOULDN'T. HE HAS CHANGE THE ONLY ACCOUNT YOU USE IN CASE OF FORGOTTEN PASSWORD( ADMISTRATOR). NOW I'M STOCK, I CAN'T DO MY HOMEWORK OR ANYTHING. CAN SOMEONE PLS TELL ME HOW I CAN REMOVE THE ADMINISTRATOR PASSWORD. NOTE: ANY TIME I USE THE F8 KEY AND START WITH NETWORKING I'M REQUIRED TO ENTER A PASSWORD EITHER FOR MY ACCOUNT OR ADMISTRATOR. NOW MY STUPID BROTHER CHANGED IT AND HE'S ON A TWO MONTHS VACATION. HOW CAN I CHANGE IT PLS SOMEONE SHOULD HELP ME OUT. i PROMISE I'D GIVE THE MOST HELPFUL SUGGESTION AND WHO EVER HELPS ME OUT 10 POINTS.Pls pls HELP ME OUT. My little (18yrs) brother has change my adminstrative password and user account. How can?
remove the password jumper. OKAY. It's true.Pls pls HELP ME OUT. My little (18yrs) brother has change my adminstrative password and user account. How can?
first of reset d cell of a motherboard. if u dont know where d motherboard cell is located than take help of any hardware engineer.this was abt bios password.

now abt windows password. there r always two users who r assigned administrative rights. one is administrator and other is (something else which u hav put during installation, mostly people keep it as own name for example ';jack'; but it can b anything).

if administrator password is changed than login from that other user.

if that other user password is changed than login from administrator account.

this way enter d OS and change d password again (if possible), otherwise keep on using it this way untill ur bro comes back.
Got a screwdriver? Turn off computer, open your case, on the motherboard is a battery (looks like a large watch battery) take it out of the board. Wait about 1 min. and replace it. This will erase all passwords and that's all. If its on a laptop remove the keyboard and look for same but it will have a plug in instead of laying flat on board. That's all tech support does and they charge $100 good luck