[B]when I was a child my mother had a car accident and claimed compensation on my behalf. I have been recently told it may be in a trust fund but do not talk to my mother anymore and cannot get any information. I no a few details e.g what car it was and roughly when but how can I trace my lost trust fund?

Although trust funds are usually held and managed by banks, they don't have to be. Your mother might be trustee. Without talking to your mother, you are making huge work for yourself for something that might not exist, or which might have been spent on your upbringing. There's a slight chance you could find something on your state site for unclaimed bank accounts (Dept of Revenue, Treasury Dept, whatever it's called), but I doubt it's there.

I have recently spoke to my brother and she has told him I have only got in contact as I am due some money so I am taking a guess it could be that but I do not no where to start or who to contact. I did ring the motor insurance beresau and they told me there is a claim under my name on the records but could not tell me no more without any details?

You need to find the insurance company that paid the settlement.