How to treat chronic ankle sprain after making physiotherapy with no heal ?

Instability: You may have lateral ankle instability. I'd be evaluated by an orthopedic foot and ankle surgeon.

Brace vs surgery: If time and pt has not helped the sensation of instability the only solutions other than living with it are to wear a brace that supports the ankle (esp. During sport activities) or a surgical repair.

IMAGING: I would do x-ray stress testing of the ankle and maybe an MRI, to further investigate the reason for continued pain.