I am aware that if a Sefer Torah were to fall to the floor the witnesses are supposed to fast for a combined total of 40 days. What about if Tefillin fall? What if they are your own Tefillin? Any difference if they were in their Batim or not? My own Shel Yad fell as I was putting it on in my home, it was not protected by anything such as its Bayit or a bag. What should I do? Thank you very much for your time and effort.

If the Tefillin fell on the floor with out their box, the minhag is to fast one day and if he finds it difficult to fast (if he works or studies Torah or teaches Torah) he can give a respectable donation to Tzedaka and do Teshuva about the unfortunate situation that occurred to him. In the case he witnessed the falling of someone else's Tefillin, he is not obliged to do anything. Rabbi Ro'i Margalit