Error occurred in deployment step ‘Recycle IIS Application Pool’: Cannot connect to the SharePoint site: http://localhost/. Make sure that this is a v

Visual studio uses the following process to deploy your solution: vssphost4.exe
Open your task manager and find the process in the list; take a note of the User Name under which this process is running, let’s say it’s myadmin_account

Now, open your SQL Management Studio and ensure this Username is added as a DBOWNER to the following databases:

SharePoint_Config
SharePoint_AdminContent_[guid]
SharePoint Site Content DB

sql permissions

Close and Open your Visual Studio again, this will ensure the service is recycled; this should fix above deployment error. If you’re still having same issue, End the process in taskmanager and then re-start VS 2010.

Good luck!