IF THE GAME CRASHES ON START UP, I HAVE A POTENTIAL SOLUTION

1.) Uninstall the entire game, then reinstall the base game, (no packs or DLC, ONLY campaign, multiplayer and zombies.) To do this, simply go to Call of Duty: Infinite Warfare in your Steam Library, scroll down to your DLC, and then click "manage DLC" uncheck everything but the base game.

2.) Start the game and preload all shaders. (this might take a while) After shader preloading is complete, start up a solo match of Zombies in Spaceland, play for a bit and then close the game.

3.) Install the DLCs (no bonus packs) To do this, simply go to Call of Duty: Infinite Warfare in your Steam Library, scroll down to your DLC, and then click "manage DLC" check all of the DLC and wait for them to download.

4.) Once installed, start the game up and preload the rest of the shaders. (this might also take a while)

Great!
Now just play the game.

idk what to say. activision/infinity ward sure as hell won't help you.
If this guide did not solve the problem, the only other solution I could find on the internet was to find the players2 folder contents and download them from somewhere or to delete the already existing players2 folder and then start up the game, neither of these worked for me.