Game crashes frequently and vstdlib.dll is missing

I downloaded the game yesterday and played it without any problem last night, but today when I started the game I got these errors: "The program can't start because vstdlib.dll is missing from your computer. Try reinstalling the program to fix this problem" and "Failed to load the launcher DLL at "***\Titanfall\bin\x64_reatail\tier0.dll" ". So I took 10 or 15 minites to repair and resinstalled the game. When I played it a few minutes later, it crashed and the same messages are shown again. I repaired it again and the exact same problem occurred again. Any suggestions, please?