Visual Studio not showing all Projects in solution

Open your ".sln" project file using Notepad. In this file you can observe listed projects like below

Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "test.myProject.Data", "test.myProject.Data\test.myProject.csproj", "{6D7F7B84-F3BD-4A19-A069-D144C345B887}"
EndProject

Please add if there any missing projects. If you have old back up or co-workers file, Just copy and paste missing projects to this file. In my case it works !!

I found that re-adding the existing project to the solution worked for me!

I had to copy out changed files in my workspace, fix my permissions/ownership on my directory (it was no owner instead of me), re-do the mapped drive the workspace was on, re-do the shortcut to the Visual Studio project (even though it was supposed to theoretically be the same place I mapped), re-pull the project down, and copy my changes in again. At this point Visual Studio had the missing solutions in it again so I could set startup project and run the debugger. I'm not sure how the ownership/permissions got messed up. I think at one point the other office had a server go down, and maybe my permissions/ownership got mixed up then. I'm not sure why VS wasn't showing the missing projects, but it's fixed after doing the above.

close vs , delete .vs folder then open vs again. it works for me.