hurting head while slipping over

It was the usuall shopping for my family. My wife an I were busy collecting the goods. Suddenly we heard the scream and cry of our little girl. She slipped on the wet floor and she hit her head aginst the shelves. We went to the hospital. Our doughter lost a lot of blood and she lost consciousness. She had to had two operations and our life tured into the nightmare. She couldn't attend classes with children in her age and since the acccident she became vey shy and a bit slow.

As you can imagine we were so concentrated  on the helth of our child that we een forgot that we may claim for the compensation. It is already  years after the accident and we would like to claim for the compensation. Is it possible to do so? How to collect all documents? How to proove that the  accident happened due to the wet floor.