I forgot my Samsung STH-N375 Lock Code

I am in desperate need of help :cry: . My brother changed his code and he forgot what he changed it to and the only security code I know for sure is my security code which is "12345." Please tell me what to do and how to enter it on the phone because when I put on the phone all I see is two options, Unlock and SOS. If I try to enter anything before selecting an option nothing is happening and when I select Unlock, well it only accepts four digits in numbers and nothing else and when I select SOS it only has my Local Police numbers and they are no help with this problems. PLEASE HELP ME !!!!! :sad: