Whole line in c# regex?

Question

Regular Expressions

Good afternoon, There is a lot of text divided line by line,
i.e. in each line a certain number of characters - then a break.
It is necessary that when a word is found, all lines where the given word exists are written to a buffer or variable, and anywhere.

var s = File.ReadAllText(textPath.Text);

                    Regex regex = new Regex(@"text", RegexOptions.IgnoreCase | RegexOptions.Multiline);

                    MatchCollection matches = regex.Matches(s);
                    if (matches.Count > 0)
                    {
                        foreach (Match match in matches)
                        {

                            // Write the string array to a new file named "WriteLines.txt".
                            using (StreamWriter outputFile = new StreamWriter(System.IO.Path.Combine(@"C:\", "mq.txt")))
                            {
                                    outputFile.WriteLine(match);
                            }
                        }
                       
                    }

The code in the regular expression is not correct, I know

Answer 1

(^.*text.*$)
^ - start of string
$ - end
.* - any number of any characters