Hello doctor, my brother is 16 years old and he is unable to walk since his birth . he walks by holding to walls . can you help.

Many possibilities: Need information like: how long has it been present and did it begin all of sudden? Are there any coexisting symptoms? What happened at before, during & after birth. A thorough neurologic examination, screening tests of strength, muscle tone, coordination, the vestibular system, the conscious proprioceptive system, and cortical function (especially the frontal lobes) must be performed.

Must be : Something congenital or birth injury since as you stated it was since birth. You need to take him to a neurologist for diagnosis and go from there.