The reason for this can be due to a Word crash. Word sometimes will unload the Ribbon.
Before following the procedure below, on the problem PC, Exit Word
and check the Startup folder for any temp files. If they exist delete
Start MS Word
Ask the person if they can see their Developer tab.
If they can't see it, in 2007, direct them to select Word Start button > Word Options, and in Popular, check the Display Developer Tab in Ribbon option (under the first screen that is displayed).
Click the Developer tab.
Click Word Templates. This will list all the addins that are loaded, APPS FOR OFFICE should be one of them.
Click APPS FOR OFFICE
If APPS FOR OFFICE isn't included in the Addins list,
Click the Add button,
Navigate the Startup folder,
Select APPS FOR OFFICE,
Tick it, and