private void button1_Click(object sender, EventArgs e)
    {
        SendKeys.SendWait( textBox15.Text + "{ENTER}");
        SendKeys.SendWait(textBox2.Text + "{ENTER}");
    }

Process myProcess = new Process();
        myProcess.StartInfo.FileName = @"C:************.exe";
        myProcess.StartInfo.WorkingDirectory = Path.GetDirectoryName(myProcess.StartInfo.FileName);
        myProcess.Start();