PLease visit this link :- http://developer.appcelerator.com/question/150991/unable-to-detect-android-sdk-targets-since-ti-studio-31
Here user is setting basic set up using terminal(Mac)/Command Prompt(Windows). try using ti setup command.
It should be solved.
You can visit this link where problem is discussed :- https://jira.appcelerator.org/browse/TIMOB-13429