If you are using custome password recovery the just have to send the mail to the user that your password is:
protected void btnSent_Click(object sender, EventArgs e)
{
string toEmailAddress = "UserToWhomSendPassword@gmail.com";
string GmailId = "xxx@gmail.com";
string password = "xxx";
SqlDataAdapter da = new SqlDataAdapter("Select uname,password from user where username='" + TextBox1.Text
+ "'", "ConnectionSTring");
DataTable dt = new DataTable();
da.Fill(dt);
string bodyMsg = "Your Username :" + dt.Rows[0]["uname"] + "and passowrd:" + dt.Rows[0]["password"].ToString();
MailMessage mail = new MailMessage();
mail.To.Add(toEmailAddress);
mail.From = new MailAddress(GmailId);
mail.Subject = txtSubject.Text;
mail.Body = bodyMsg;
mail.IsBodyHtml = true;
SmtpClient smtp = new SmtpClient("smtp.gmail.com");
smtp.EnableSsl = true;
smtp.UseDefaultCredentials = false;
smtp.Credentials = new System.Net.NetworkCredential(GmailId, password);
smtp.Send(mail);
}