Broken laptop

Hello, my name is Tracy I just bought a laptop second hand its a dell latitude 2100 10'1" Nitebook Window 7#Item#182191891312,its tell me that the computer system,#24D6SN1-2A7B,is protected by a password authenication system and I cant accessthe data without that pass word and then it ask for a system or administrator password,so how or who i get this information from cause I only had the computer since July 10,2016 or I need to send it back