The test plan with id 328 does not exist or it’s area path is not owned by the default project team

We are trying to access Test plans using the Web interface from Test Manager 2013 and we keep getting this message.

The test plan with id 328 does not exist or it’s area path is not owned by the default project team.

I read in another post that a fix would be to open the ROOT Test plan in Visual Studio and save it.

I don't know how to do that, can someone please let me know how or point me to somewhere I can learn on how to do that.

Thank you!

Bill