The language of the menus, etc., in Mail.app changed into Catalan. I would like to have it back in the system default language. So far, I have tried (1) restoring Mail.app file from the Applications folder in Time Machine, (2) copying the Mail.app file from Time Machine to Desktop and then moving to Applications folder, and (3) installing App Language Chooser from AppStore. None of them worked. The first two refused to replace the existing Mail.app because the system needs it; the third had no effect whatsoever. I have a MBP with preinstalled Lion with latest update (10.7.4) and the whole system backed up to Time Capsule. Can I somehow reinstall Mail.app? Or, can I restore a working version of the Mail.app from Time Machine? Or, should I try restore my whole system to the latest working configuration from Time Machine? (I am not sure how to do this.) Or, would I need to reinstall the whole operating system? (I'd rather switch to Thunderbird or Sparrow than do this.) My backup plan is waiting a few weeks and updating to Mountain Lion.