Instructions
Check to make sure you haven't already unlocked the achievement. When you're in the heat of the moment and unlock an achievement, you can sometimes miss the notification. When you go back to unlock the achievement, you can go through the motions over and over and never receive any notification. By pressing the Xbox Guide button, moving to the "Games" tab, selecting "Achievements" and then "LEGO Batman," you can go through your achievements to see whether you've unlocked them or not.
Ensure you're meeting the requirements. Some achievements in "LEGO Batman" demand that you meet certain prerequisites that aren't listed in the achievement description. One example is the "There and Back" achievement, which requires you to destroy 10 objects with a Batarang. What some don't realize is that you have to destroy 10 objects with a single Batarang throw.
Disable any cheats you have. Certain in-game achievements will become inaccessible if you have certain cheat codes on. If you are looking to unlock certain achievements, you need to make sure your cheats are turned off. You can do this by pressing "Start," go to your "Extras" menu and make sure everything is turned off.