How to find & replace text in word document in bulk using c#.net?

if you want replace all word at a time

step1: store all word in a list

List<string> wordsToReplace = new List<string>() { "age:-21","salary:-20000","Name:-vikas" };

step2: create an expression

string replacementString = String.Join("|",wordsToReplace);
step3: store document

string fileContent = System.IO.File.ReadAllText(Server.MapPath("~/TestFile.doc"));

step4: Perform replacement
fileContent = Regex.Replace(fileContent,replacementString, "animal")

step5:write contenet

System.IO.File.WriteAllText(Server.MapPath("~/TestFile.doc"), fileContent);