My note app deleted a part of my notes.

I was studying for my final exam that I have to take this week and I was writing my analysis using the note app on my iPad then suddently the app closed by itself and when I reopened it and went to the note I was working on, half of what I had written had disappeared. Is there anyway I can retrieve it, the way it was written was perfect and I don’t remember it nor do I remember half of what was written.