My computer is dying please help

Hello, my daughter changed the amintration acount to her account and to add insult to injury she cant remember her password i had her on a time restriction and i had fill them all in so she had no time so i dont know if thats a facter all i know my computer dying without protection did i mention she deleted my anti verus before she did that so now i cant do anything with it help please its a dell running on vista thanks