Can't connect to SQL Server database from C#
<p>I've installed and reinstalled SQL Server 2014 Express and Visual Studio, still it won't let me connect to a database. It won't even let me create a database. </p>

<p>Here is a the error message:</p>

<blockquote>
  <p>The Data Source value in the connection string specifies an instance of SQL Server that is not installed. To resolve this issue, you can either choose to install the matching instance of SQL Server or modify the Data Source value in the connection string.</p>
</blockquote>

<p>Has anyone encountered this before?</p>