How to ReInstall Podfile in the project?

I have downgrade my operating system from Mac Os Sierra to el Capitan, so all the files were removed from my system,but i have done backup my project. Now when i have opened my project for running .Workspace file it shows me empty in my project. So please tell me i have used google places api in the project but project is not working . I have done pod installation then this error is coming when i click on Main.Storyboard. What to do Please help me what to do?