How do I file c case for negligence for my father?

My father was admitted in the hospital on last week and they always display a sign fall at risk. My father fell out the bed last week and broke his hip. No one called me to let me know. I called the next day to check on my dad. That's when I found out he fell and broke his hip. No one notified me. I had to find out on my own. Then I got a call from the nurse that was watching my dad. She told me that she was sorry for not calling me and let me know my father fell out the bed. I said you're a little late because I found out on my own when I called to check on my father. The hospital called me later on that day and told me that my father have to have a hip replacement and he will have to go into rehab.