AppSettings get value from .config file

The answer that dtsg gave works:

string filePath = ConfigurationManager.AppSettings["ClientsFilePath"];

BUT, you need to add an assembly reference to

System.Configuration

Go to your Solution Explorer and right click on References and select Add reference. Select the Assemblies tab and search for Configuration.

Here is an example of my App.config:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
    </startup>
  <appSettings>
    <add key="AdminName" value="My Name"/>
    <add key="AdminEMail" value="MyEMailAddress"/>
  </appSettings>
</configuration>

Which you can get in the following way:

string adminName = ConfigurationManager.AppSettings["AdminName"];

This works for me:

string value = System.Configuration.ConfigurationManager.AppSettings[key];