I have an add-in that usually shows when I'm in the Admin console. But I don't currently see it.
Admin Console / Add-In
There are a few possible solutions to this issue:
A) If the profile your staff account is associated to does not have the add-in selected, the add-in will not show. It is possible that an administrator removed that permission from your profile. Have an administrator edit your profile and view the Add-In's section to ensure your particular add-in is still enabled.
B) If your previous instance of Oracle Service Cloud had died because of a network issue or other issue, you may have been prompted with this upon your next login: "The application did not exit properly the last time it was started. Would you like to temporarily disable extensions that may have caused the application to behave improperly?"
If you clicked Yes in this prompt, your site would have loaded without any add-in's enabled. Simply logging out and back in should resolve it. But just make sure to click 'No' in that prompt if it comes up again if you have add-in's you need to access.
C) Although uncommon, the Add-Ins folder for your site may have been corrupted or did not download correctly. You may need to delete the add-ins from that folder and re-launch Oracle Service Cloud to reload it. Location of AddIns folder:
Windows 7 and above: C:\Users\<your windows login>\AppData\Roaming\RightNow_Technologies\<your site>\<version number>\Users\<user number>\AddIns
version number – Version of Oracle Service Cloud, use the highest number.
user number – Account ID of user(s) have logged in to the console. Usually there will only be one. If in doubt, delete the Addins folder for each one.