How much compensation can I claim for a back and head injury from a taxi accident?

[Elly]

I was on my way home in a black cab when we got into a bad car accident, we crashed into another car and it was not the taxi drivers fault.
I was thrown from my seat and knocked unconscious and had to go to hospital, I had a severe concussion and I have been suffering terrible back pain with whiplash.
How much could I be entitled to for an accident like this?