switching back to old company?

Hi *,

two years ago I changed my job from an IT manager into another company with a lower position. This change was not for any personal reasons – the subject sounded better. Half a year I changed back into a lower position (this time for personal reasons). Now I have two questions:
1. Generally: is it a good idea to switch back to a former company?
2. What can I do push my carreer again? Hwo do I re-establish reliability?

Andreas