.net - Developing valid xhtml document from unformed html -

I want to develop a valid XHTML doctor, the input dock is not well formatted, I am successful in getting caught up in the situation like

  & lt; Span & gt; ...... & lt; P & gt; & Lt; / Span & gt; ... & lt; / P & gt;  

There can be any tag in place of Span and P ... but in the situation it is said that I want to handle this situation. New C # PLJ is essential. ... thanx

This is a good tool to validate and correct XHTML. ..