Office products such as Word, Excel Outlook will automatically disable installed add-in if any add-in prevented the software from functioning correctly. And it also provides option for enabling the disabled add-in items. In Excel 2010 you can enable a disabled add-in using the add-in options.
Click the File menu –> Options link –> Navigate to Add-Ins options.
Select Disabled Items in the Manage dropdown and click the Go button. This would display the following Disabled Items window using which you can see and also re-enable the disabled add-in. You can select the ones you wish to re-enable and click the Enable button.