Given the following
(Where the line and column number represent the \'<\' charact
See LINQ to XML and Line Numbers on LINQ Exchange gives an example using IXmlLineInfo that corresponds to what you're looking for:
XDocument xml = XDocument.Load(fileName, LoadOptions.SetLineInfo);
var line = from x in xml.Descendants()
let lineInfo = (IXmlLineInfo)x
where lineInfo.LineNumber == 21
select x;
foreach (var item in line)
{
Console.WriteLine(item);
}