Help - Lost all data

A friend of mine recently lost all her data after opening the app a couple months later. When she opened the app it looked like it Was reset, has anyone ever had a problem like this?

She had an ipad air, her recycle bin was also empty , she aaked for my help but even i don't know how to solve this problem and how the data got lost. Can anyone help? I know without a backup it's very difficult to bring back any data but is there any way to bring her data back?