"project could not be loaded" in Visual Studio 2019

Question

I have a solution file, solution1, which has two projects

One is Azure webapp and one is web service. When I'm opening the solution, the webapp is loading properly> However, the web service project loading failed saying (ws1(unloaded)).

The error:

D:\Path1\path2\ws1.csproj : error : The project file could not be loaded.could not find the part of the path
D:\Path1\path2\ws1.csproj

When I clicked on "reload project", it's showing error windows saying "The operation could not be completed"

I see another message saying, ws1.csproj has been moved,renamed or is not on your computer. When I went inside the ws1 folder, I see the .csproj file name and type is as below:

  name: ws1.csproj.user
  type : Per-User Project Options file

The above name and type is really confusing. I an unable to understand what this type means?

It looks like, the ws1 project is separated from the solution and I can see it's kept outside the folder in which the solution file is.

Is there any way to resolve this issue?

Note, I have kept the ws1 project in the same folder where the solution file is, however, the issue is not resolved.