First, please validate your files, by right clicking on the game title in the Library of the Steam client. Then pick: Properties > Local Files > Verify integrity of game cache.
Please ensure that your video card drivers and DirectX are completely up-to-date. We recommend that you uninstall the drivers for your video card completely, then go to your video card manufacturer's website and manually download the latest drivers.
If you're seeing black screen/crashing after just changing your resolution you may have swapped to an unsupported resolution that your monitor does not support.
1. In the Steam client, navigate to the Games tab
2. Right click on "BattleBlock Theater" from the game list, then select the "Properties" menu option
3. Under the "General" tab, click the "Set Launch Options" button
4. Copy-paste the following into the box: -windowed
This will force the game to launch in windowed mode! Set the correct resolution for your monitor in-game, under Help and Options > Game Settings > Resolution.
You can also swap to Full-screen mode here too, but be sure to go back and delete the " -windowed" from the launch options box later, or you'll have to change your settings every time you boot!
If nothing helps, please open a ticket with our support team. It would be a great help if you included the text of any error messages you received, whether you have ever been able to play BattleBlock in the past, and what you were doing directly before the crash. Thank you!