C# Program Update or SQL EXPRES Database Backup

send me your whole code

Hey thanks a lot for these codes, it seems like this is what im loking for, but i get in an error :
it says this message : 
                                Database 'TEST' does not exist. Make sure that the name is entered correctly. Backup Database is terminating abnormally.

I put the right name in the codes but i dont know why cant i backup it (i think it might be that i use an internal local database). Pls help me solve this

For Backup

SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=your_database_name;Integrated Security=True");
            con.Open();
            try
            {
                SqlCommand cmd = new SqlCommand("backup database email_client to disk ='" + path+ "\\" + name_you_want_to_give_to_database + ".bak'", con);
                cmd.ExecuteNonQuery();
                MessageBox.Show("done");
 }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
Div
 For Restore

 SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=master;Integrated Security=True");
            con.Open();
            try
            {


                sql = "alter database your_database_name set single_user with rollback immediate ;";
                sql += "RESTORE database your_database_name from disk='"+backup_file_name+"'with replace;";
                cmd = new SqlCommand(sql, con);
                cmd.ExecuteNonQuery();
                con.Close();
                con.Dispose();
                MessageBox.Show("done");


            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }