hi its me again.

some how the passwords for the family pc got changed , in fact it was never password protected, as far as i know. but now there is a password on all accounts even the administrator one . and no one seems to remember the passwords. we recently changed firewalls, which i doubt has anything to do with it, from zone alarm to comodo. is it possible that some one can access the computer via internet and change our passwords . i dont know for sure, im new to networking and the such, but either way i need to recover those passwords or change them. any suggestions? thnx for the help

runnin windows xp professional sp2 i do believe