Step 1 - Click Start, Scroll down to the Ws, Click on the Windows System folder, then click Control Panel

Step 2 - Click the categories button at the top right, click on Small Icons, then locate and click on Programs and Features

Step 3 - Locate and click only once on the Office item in the list. Then, click on the Change button at the top and then click yes when it asks for permission. 

​Step 4 - Start with a Quick Repair. Select the option button next to Quick Repair and then click the repair button at the bottom. Let it run, reboot your PC after it finishes and see if everything is working again. If it's not, follow this through step 3 and then try Online Repair the second time.