mail app: dock count gone

Is there any way to restore or reinstall mail app? Without having to reinstall the whole computer? My dekstop does no longer show me the dock count for my mail app unread folder. It still works on laptop and ipad. It's a little annoyance... I tried to set it back up in the preferences, but even though it says that it will count there it does not show me any badge in the dock. What is wrong? I also repaired permissions...