How can i reset my alarm?

I have just moved into a new home with a securitech alarm system which is quite old.My 2 y,o son was messing with the buttons and now the alarm box inside is making bleeping sounds and i dont have a single clue how to get it to stop.I dont know if the previous tennents knew the code and i dont know the last time the code was set.My landlord told me to contact the firm but i cant find one in the uk only usa.I would apprecite any advice at all.Thanks