I just had to press "retry" for it fix itself.
But if this is not the case, one way to solve it is by doing following:
1. Go into your %appdata% folder > Roaming > Splitscreen Studios > Pirate Galaxy > Game Data > Pirate Galaxy
2. Delete the "files" folder. (this way your screenshots will still remain intact)
3. Launch the game and it should automatically re-download the files and launch the game.
NOTE: When you do this, your settings in game such as sound, and graphics quality etc will be reset to default.
Heriiwax