Expired CFI Certificate, now what?

I get many mails regarding flight training; one of the questions is how to reinstate an expired CFI.
Well to put it simply, if your CFI has expired, you have to take the exam check ride again, with a designated FAA examiner.This includes both the oral part of the exam, and the flight check.
You can also reinstate your expired CFI, by adding a new rating to it, for example, if you had CFI, CFII, you can add the MEI multi engine instructor. When you have passed the check ride for the MEI, all your ratings on the CFI certificate will be reinstated.
The same if you hold a bare CFI, then you can either choose to add CFII and/or MEI.
So like you can see there are options, to get your CFI back on track.