[ubuntu] Clock and Calendar disappear from the panel

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http://ubuntuforums.org – So I recently upgraded from 10.04 to 12.04 and since I am now using Thunderbird instead of Evolution as my email client, I removed evolution from the system, I wasn't aware that date and time was dependent on Evolution. And so now there is no Date Time appearing in my panel. I've re-installed evolution since then but date time is still not visible. I can't even see the date-time option in system settings. Can somebody please let me know how to get it back? Thank you in advance. (Hardware)