It seems like you have got a corrupt solution. I do not have an elegant solution, however I think only Rebuild should help as it internally cleans first and then builds the solution.
See
here[
^]
Also may I suggest a work around? Can you create a brand new solution and add projects one by one and build and play? That way you can narrow down which project is corrupted. And then may be you can recreate only that project.
Please up-vote the solution if it helps and encourage participation. Thank you.