No contact

My father died 3 years ago, we were a very close family, 1 older sister, our mum was the one who took care of finances, mum & dad had saved all their life to leave an inheritance to leave us and their 3 grandchildren, the amount was 50,000, my elder sister who is high up in a position of trust in local government advised mum that the money in her account would mess up her pension an get her in trouble, she advised mum to give her the money and she put it in 5 separate building society accounts in her name not mums, she also has the cards for these accounts.
She then took mum to a solicitor after dad's death and make a will and naming her as executor and giving her power of attorney and access to her bank accounts, one of which had 10,000 for her funeral and other money to clear and bills on her death, as well as mum's saving accounts, I was never told the amounts in those accounts.
After dad died I moved in with mum for months and when I stopped staying there I was still going there dsily as my sister was to busy, once my sister had finished her house renovation she took over and pushed myself and mum's granddaughter (my daughter) out and made it impossible to contact mum, in Jan we were told mum had cancer an had surgery but we weren't needed, we called there, phoned, I wrote letters, cards and sent flowers ( I was having surgery for my own cancer the day we found out about mum) it took me weeks to get better then lockdown happened, still no contact made, we were then told by a distant relative mum had died, my sister didn't tell us, we were not told about family cars, flowers ect even the wake was a secret, we were treated like strangers, It came to light mum had been in hospital a long time and my sister dealt with her mail and never passed on out letters and cards ect, I can only assume she told mum we didn't care, I know the solicitors where the will was made 2 years ago but no proof of inheritance she has, my question is what do I do? She's since cleared out mum and dad's house of everything and handed they keys back to the housing, I feel this was all premeditated by her to block us out financially, with no mention in the will of money and she advised mum not to.