I just tried ran the Minecraft Launcher and it updated to version 1.6.73. Now if I run it and click Play the launcher disappears for a second (as if the game is launching) and then it just pops back up with some messages in the Game Output Tab. Please see the Launcher Logs and Game Output attached
Duplicate of MC-112780. If you have not, please use the search function in the future to check whether your bug already has been reported. More than 50% of all bugs ever reported had to be closed as duplicate.