My new question today is: Is there an "undo" button?? I was typing an extensive HPI and pressed some series of keys that quickly highlighted the text and then deleted it. I know that I caused it but I was hoping to find an undo action that would make it return.
Ctrl-z is Undo. It doesn't always work, but it is always worth a try. In the example you site, clicking in a box in the encounter (e.g. in HPI) will often (but not always...) select all text, and then hitting "enter" deletes the whole box. That is likely what you did accidentally. Ctrl-z brings it back.