Does everything happen for a reason? If something unexpected (and incredibly unlikely) happens, should we take it as something deeper or just a fact of life?

Something highly unlikely and very positive happened at a very bad and negative point in my life, this event arguably showed a very different future to the one I imagined.

Don't know how to read into it, or how my actions should be after the event, should I embrace the change?
My teacher taught me that I must choose how I interpret such events in whichever way that produces the most wholesome mindstates.

So if thinking that this event was a sign from the hidden nature of things and held special significance makes you stronger, go for it with no hesitation. This is called, utilizing the power of faith.

In Varjrayana we learn to see hidden connections between things, hidden patterns and relationships. So having a sense of intuition for special events in one's life is important in our practice. In the absence of egoistic desires, and the baselessness of Emptiness, how else can we pick the course of action? So we choose to interpret things in a certain way, and act based on that. It's more an art than a science but there is a system to it.