Why isn't my iPhone sound working?

The ringer works in the settings but no videos have sound? Not on Instagram, YouTube or even gallery? It shouldn't be the speaker though because I can hear the ringer sound in settings

How can I get onto a iPhone when I don't have the passcode?

My sister passed away over a year ago and I've been meaning to find a way of how to get onto her IPhone 5s for ages now. She has loads of photos and videos on there, just tons of memories, that I want to see. Is there a way to can get onto there without deleting everything?

How do I gain access to my facebook again?

A few days ago I had to restore my iPhone and I have to log into facebook all over again and whenever I log in it asks for a code from code generator to verify my log in but its linked with my old number so I can't access thecode anywhere else. Is there a way for me to log in without I or am I screwed?