Since we don't know the underlying cause for the problem, a reinstallation won't necessarily work.
If you do attempt a reinstallation, make sure that you have all the information required to install Office (a Microsoft account and/or a product key). Also, you will have to remove all traces of the installation first, which is discussed in the article at
https://support.office.com/en-us/art...rs=en-US&ad=US.