how to parse json in asp.net using c#

hi,
   how to parse json from post method in asp.net using c# i got data from post method but unable to convert into json
 NameValueCollection nvc = Request.Form;
System.Text.StringBuilder displayValues = new System.Text.StringBuilder(); System.Collections.Specialized.NameValueCollection postedValues = Request.Form; String nextKey; for (int i = 0; i < postedValues.AllKeys.Length; i++) { nextKey = postedValues.AllKeys[i]; if (nextKey.Substring(0, 2) != "__") { displayValues.Append("<br>"); displayValues.Append(nextKey); displayValues.Append(" = "); displayValues.Append(postedValues[i]); } }
string newdata= ConstructQueryString(nvc); string s = postedValues.ToString(); StringWriter writer = new StringWriter(); ViewStateParser p = new ViewStateParser(writer); string json = s; //string[][] newK ...