- First try to repair your installation - First try Quick Repair (takes 5 - 10 mins) , if that doesn't help then try Online Repair (Takes more than 30 mins but less than 1 hour in general)
https://support.office.com/en-us/article/Repair...
- You may have 2 MS Offices installed on your system
A. Run FIX IT tool to remove previous version - https://support.office.com/en-us/article/Uninst...
B. Perform Online Repair of new Office. Takes more than 30 mins but less than 1 hour in general)
https://support.office.com/en-us/article/Repair...
- Try Activation Troubleshooter and other troubleshooting steps
https://support.office.com/en-us/article/Unlice...
- Try to activate through telephone
https://support.office.com/en-us/article/-Telep...
- Talk to support
https://support.microsoft.com/en-us/help/13948/... (Click on the starting alphabet of country name. Hence for US, click U)
- You may try chatting with MS Support to resolve this issue
https://partner.support.services.microsoft.com/...
- Alternatively, you may also e mail to MS Support for account help