C# win frm timer countdown with user input

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C#

Visual-Studio

please help me,
i would have a user input in textBox1 for my timer countdown,

What I have tried:

this is my code:


using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Diagnostics;

namespace Timer1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

private int counter=80;
DateTime dt = new DateTime();
private void button1_Click(object sender, EventArgs e)
{
progressBar1.Maximum = counter * 1000;
progressBar1.Step = 1000;
timer1 = new System.Windows.Forms.Timer();
timer1.Tick += new EventHandler(timer1_Tick);
timer1.Interval = 1000;
timer1.Start();
textBox1.Text = counter.ToString();
}


private void timer1_Tick(object sender, EventArgs e)
{
counter--;
progressBar1.PerformStep();
if (counter == 0)
{
timer1.Stop();
}
textBox1.Text = dt.AddSeconds(counter).ToString("mm : ss");
}

private void Form1_Load(object sender, EventArgs e)
{
timer1.Enabled = false;
}

private void button2_Click(object sender, EventArgs e)
{
timer1.Stop();
textBox1.Clear();
progressBar1.Value = 0;
}

private void textBox1_TextChanged(object sender, EventArgs e)
{
button2_Click(sender, e);
}
}
}