Q: I lost my iphone6 plus but right now I cant see in my list under iCloud a while ago I can see it but no it's gone !

AStolen my iphone6plus yesterday I can see my iPhone 6 plus in my list find my iPhone but right now I was wondering why my iphone6 plus was not appear in the listing what's happen??? they unlock it or maybe they can broken my iphone already ? My next question is from time to time I will check my iCloud but many time I enter my passport they said incorrect pass pwes pls reset your password what is that ? What happen ? Please help me only three week when I was brough this unit so sad . Please help me to find and back my unit . Who know here in philippines therea a lot of technician doing well is it possible to unlocky iPhone?