My boy friend id 17 years old and he got in a four wheeler accident this past summer and his back is hurting his parents eont tske him what can i do?

Go for a walk: Get him up and moving. If walking is too much, do stretching and calisthenics with him.

Question isn't clear: If a 17 year-old has back pain that is moderate pain or worse, or is having trouble moving around or doing sports, he needs an evaluation. If parents won't take him due to lack of money or due to immigration status, he can ask a local Teen Clinic, which is often connected to the County Health Dept. or to a medical university. Teen clinics may be able to see teens for free (one can ask the clinic).