Maybe you could start by allowing her to see her friends. ? she is 15  friends are a big role in a 15 yr olds life I used to run away at this age and believe me the more you tell her not to go out seeing her friends the more she is going to. Sorry if that seems harsh but im just thinking the way your daughter would

They have made a bad decision. They got themselves caught up in pressures that they felt the need to escape from. Instead of facing their problem and solving it, they chose to run from it. We need to teach our teen how to face their problems, even if the problem is us. When they have the right tools to fix some of the things that may be going on in their lives, the pressure lessens, and there is no more need for them to escape.

Why is she not allowed to see her friends?

Friends are very important to young girls, and especially at that age, if parents impose too many rules, are too strict, or don't let them have contact with their friends, THAT is why they run away. To get the freedom they crave, even if they don't yet realise how hard it is to support themselves.

I don't know about your girl, but I ran away at 14 because I just wanted all the arguments between my parents and I to stop. I figured if I was free of them they couldn't bother me. Oh, and boys will just about always be able to get 14 year old girls to do just about anything - especially running away together.