SPOILER ALERT

So i am on the mission where you and Psyco are in the VTOL and it crashes onto the building and you kill alot of ceph. Then you are flying away and a "new form" of ceph pulls you out, i fought the boss and it said hit space repeatedly, i did so and then it said i was dead, and hit enter to retry, i did so and i spawned with the "boss" not being there and i walked around for a bit on the rooftop and the boss never arrived so I quit campaign ad tried to load it up again and now every time i try to resume game, I hear a very short blast of in-game music then it stops responding?
I wanted to hear any suggestions before reinstalling or anything of that nature!

You should go back to the game menu to your current campaign and select LOAD (which lists the previously completed checkpoints). Choose the latest one and continue from there. I think that mission's checkpoint will be right after you are pulled from the VTOL by the Ceph Mastermind and then the battle begins.