To chime in with the others, yes, UNDO was your only option.
For the future: To undo, press the .?123 key on the left side of the keyboard. An undo button will show about in the same place. Pressing that will undo any actions. Do note that it will undo all the way back, in steps. So, if you delete something in one step, it'll undelete it. Then, if you press undo, the step you did before the delete will be undone.
For example, I typed "test test test." Then, I highlighted the last two "tests" and hit the delete key. Then, I pressed the undo key and the two words came back. Then, I pressed undo again and all the words disappeared (which was the last action I performed before the delete...typing the three words).
Hope that made sense. Oh, and do remember, there is no REdo key. It's undo or nothing. And, if you leave the note before applying the undo, it won't work.
Sorry this is too late for your situation - but maybe this info will help in the future.
Marilyn