You can try to fix the problem by repairing Microsoft Office online:
1. Click on Start and open the Control Panel
2. Select Programs and Features
3. Click with right mouse button on Microsoft Office and choose Change
4. Then, the window below should appear. If possible select Online Repair
and click on Repair button:
After the repairing, you have to restart the Microsoft Office. If the repair doesn't work, you can try to uninstall and reinstall it.