Cannot edit site in Visual Studio

We are using Sitefinity 8.0 and when using project manager and select 'edit in visual studio' it returns: SitefinityWebApp.csproj does not exist

Is there a way to create this file?

When I try to create a new project, it returns: You have requested a file from older product minor version

I tried to download version 8.0 again but cannot find it at your site.

Can someone tell me where I can file this version?

Thanks.