My game project wont start

So today at night time I was working on my game project and I was doing some terrain clean up what I noticed is that the Navigation was being updated even dough the navigation box was no were in that location I tought it was pointless but it kept updating.

The next thing was that I went down to the kitchen and came back up to my room to test out my changes and I forgot that the navigation mesh thing was still updating it halted for what felt like 10 seconds and it closed Unreal Engine 4.

I tried relaunching my game and no dice it refuses to open it only shows the splash with the name of the game but its not opening it.

Whats going on and how can it be fixed?

Hey Elizabeth,

Can you post this as a bug report on the AnswerHub? That would help us a lot with tracking the issue and assigning a technician to look into it. Thanks!