Also, part of having bitachon in Hashem means not second-guessing ourselves, and recognizing that everything, including the results of our actions comes from Hashem. If someone’s Tefillin gets lost (certainly in a case like this where he didn’t do anything that would have been considered a problem halachically – he put his Tefillin in the same place that everyone does and that is considered the normal place to put Tefillin), one must believe that it was from Hashem and not feel guilty about it.
I think that is one the hardest nisyonos. I know it’s something I find very difficult. I am continually second-guessing myself and thinking that thing a) must have happened because of a certain wrong decision I made, etc.
But a believing Jew is not allowed to think like that. We have to remind ourselves that everything comes from Hashem, and even if we made poor decisions, they don’t cause bad things to happen to us- everything comes from Hashem and is for our good, period!!!