This varies from machine to machine. I have a Bernina, and as you sew the display shows where on the stitch you are. If you wish to re-start, it has a button that re-start the stitch.
If your machine doesn't re-start, you need to run the stitch slowly and watch how it runs.
Ex: The button hole starts up/down, left, right, forward, backward, forward, left, right
Double button hole is up, down, left, right, left, right, forward, backwards, forward, backwards, forward, left, right.
If you need to restart the stitch, you may need to select another stitch and go back to the one you wish.