Please try these options one by one and check after each option.
- Try repairing your office installation (Quick repair is good enough). Try repairing your Office 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...
- Sometimes, add-ins can cause problems. To determine, if add-in is a problem start your application in safe mode and see if problem has gone away.
To start in Safe Mode -
Hold CTRL key and click on application icon and don't release the CTRL key till it asks you for Safe mode confirmation.
If yes, then start application normally and disable add-ins one by one and start application again every time you disable an add-in to determine the culprit add-in.
To disable add-in > File > Options > Add-ins > Down below you have Manage: Com Add-in : Press Go > Untick the Add-ins to disable and tick to enable them
Do let me know if you have any more question or require further help. If above didn't work, I will supply more troubleshooting steps to solve this problem.