I accidentally highlighted a note and hit the keypad erasing everything I had worked on. Can I retrieve what I lost?

If that happened to me, I would try the following:

1. "Shake to Undo" - perhaps you have that function in place. Shake the iPhone a bit and see if you're offered an "Undo" option.
2. "Undo the last edit" - Swipe left with three fingers. If you see an "Undo" option at the top of the screen, accept it.

Yeah i wanted write the same thing rn + if u have a keyboard try pressing command+z or control+z

but! If you closed the file, you cant go back!