C# Xml Manipulation: Replace InnerText of Node

Just loop through your xml structure using xPath as usual then call the InnerText property to set the new value.

 
XmlDocument xdocLocalFile = new XmlDocument();
 
xdocLocalFile.Load("MyXmlFile.xml");
 
foreach (XmlNode xNodeReplace in
           xdocLocalFile.SelectNodes("root/phunk"))
{
           xNodeReplace.FirstChild.InnerText = "My new Value";
}