How to undo fill-paragraph in emacs?

Use the following from my .emacs:

(defun unfill-paragraph ()
  (interactive)
  (let ((fill-column (point-max)))
    (fill-paragraph nil)))

(defun unfill-region ()
  (interactive)
  (let ((fill-column (point-max)))
    (fill-region (region-beginning) (region-end) nil)))

I can't take credit, I googled this years ago.

You can set fill-columnn to a really large number, and fill.

C-u 10000 C-x f M-x fill-individual-paragraphs

Or you can use a little custom function:

(defun refill-paragraphs-to-be-one-line ()
  "fill individual paragraphs with large fill column"
  (interactive)
  (let ((fill-column 100000))
    (fill-individual-paragraphs (point-min) (point-max))))