Unreal Engine Crash on start

Hello i create a simple multiplayer project everything it goes perfectly until Unreal Engine Starts acting strange, here is my problem. I play my game yesterday every was great, today i launch Unreal Engine make a little bit of changes in my BP’s and when i click 2 player play - No matter if its Selected Viewport or PIE, Soon as second player screen shows up UE4 Crash. IDK what is happening i go back to UE4 Restore my little changes and still nothing, again crash when i play with 2 players. But when i start as a 1 everything works without any error or warning !
Now i can’t test my game i can’t continue with my project without testing if it’s works or not !
can someone help me with this one ?