string replaced = original.Replace("\n", "n");

string EscapeLikeALiteral (string src) {
    return Regex.Replace(src, @"\(?<simple>['""\0abfnrtv])", (m) => {
       var s = m.Groups["simple"].Value;
       switch (s) {
           case "'": return "'";
           case """: return """;
           case "0": return "";
           case "a": return "a";
           case "b": return "b";
           case "f": return "f";
           case "n": return "n";
           case "r": return "r";
           case "t": return "t";
           case "v": return "v";
           default:
               throw new InvalidOperationException();
       }
    });
}

var r = EscapeLikeALiteral(@"hellonworld");