Maybe some of you are having the same problem I had which is pretty easily resolved. If you have installed Boldgrid that is probably the culprit. To get back your appearance tab simply click on Boldgrid under the Settings tab and uncheck the Use Boldgrid Menu System next to Reorder Admin Menu. After you do this you will need to refresh your dashboard and then your Appearance tab should reappear.
Hope this helps, good luck!
