ช่วยทีค่ะ เกี่ยวกับการใช้ checkBox ค้นหาไฟล์ค่ะ c#

using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Diagnostics;

namespace File_Browser_Pro
{
    public partial class Form1 : Form
    {
        private string currentFolderPath;
       private string sampledriveletter = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            LoadDrive();
            //label10.Visible = true;
        }

        protected void LoadDrive()
        {
           DirectoryInfo driveletter; 
        
           foreach (char c in sampledriveletter)
            {
                string drive = c + ":\\";
                driveletter = new DirectoryInfo(drive);
                if (driveletter.Exists == true)
                {
                   DriveCombo.Items.Add(driveletter.FullName);
                }
            }
        }

        protected void ClearAllFields()
        {
            listBoxFolders.Items.Clear();
            listBoxFiles.Items.Clear();
            textBoxFolder.Text = "";
            textBoxFileName.Text = "";
            textBoxCreationTime.Text = "";
            textBoxLastAccessTime.Text = "";
            textBoxLastWriteTime.Text = "";
            textBoxFileSize.Text = "";
            currentFolderPath = null;

        }

        protected void DisplayFileInfo(string fileFullName)
        {
            FileInfo theFile = new FileInfo(fileFullName);
            if (!theFile.Exists)
            {
                throw new FileNotFoundException("File not found: " + fileFullName);
            }
            textBoxFileName.Text = theFile.Name;
            textBoxCreationTime.Text = theFile.CreationTime.ToLongTimeString();
            textBoxLastAccessTime.Text = theFile.LastAccessTime.ToLongDateString();
            textBoxLastWriteTime.Text = theFile.LastWriteTime.ToLongDateString();
            textBoxFileSize.Text = theFile.Length.ToString() + " bytes";
        }
    


        protected void DisplayFolderList(string folderFullName)
        {
            DirectoryInfo theFolder = new DirectoryInfo(folderFullName);
            if (!theFolder.Exists)
            {
                throw new DirectoryNotFoundException("Folder not found: " + folderFullName);
            }
            ClearAllFields();
            textBoxFolder.Text = theFolder.FullName;
            currentFolderPath = theFolder.FullName;
            // list all subfolders in folder
            foreach (DirectoryInfo nextFolder in theFolder.GetDirectories())
                listBoxFolders.Items.Add(nextFolder.Name);
            // list all files in folder
            foreach (FileInfo nextFile in theFolder.GetFiles())
                listBoxFiles.Items.Add(nextFile.Name);
        }

     

        private void listBoxFiles_SelectedIndexChanged(object sender, EventArgs e)
        {
            try
            {
                string selectedString = listBoxFiles.SelectedItem.ToString();
                string fullFileName = Path.Combine(currentFolderPath, selectedString);
                DisplayFileInfo(fullFileName);
                openFile(fullFileName);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void listBoxFolders_SelectedIndexChanged(object sender, EventArgs e)
        {
            try
            {
                string selectedString = listBoxFolders.SelectedItem.ToString();
                string fullPathName = Path.Combine(currentFolderPath, selectedString);
                DisplayFolderList(fullPathName);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
       
        private void buttonUp_Click(object sender, EventArgs e)
        {
            try
            {
                string folderPath = new FileInfo(currentFolderPath).DirectoryName;
                DisplayFolderList(folderPath);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            ClearAllFields();
        }

        private void DriveCombo_SelectedValueChanged(object sender, EventArgs e)
        {
            try
            {
                string folderPath = DriveCombo.SelectedItem.ToString();
                DirectoryInfo theFolder = new DirectoryInfo(folderPath);
                if (theFolder.Exists)
                {
                    DisplayFolderList(theFolder.FullName);
                    return;
                }
                FileInfo theFile = new FileInfo(folderPath);
                if (theFile.Exists)
                {
                    DisplayFolderList(theFile.Directory.FullName);
                    int index = listBoxFiles.Items.IndexOf(theFile.Name);
                    listBoxFiles.SetSelected(index, true);
                    return;
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void openFile(string openFileName)
        {
            if (File.Exists(openFileName))
            {
                try
                {
                    ProcessStartInfo startInfo = new ProcessStartInfo();
                    startInfo.FileName = openFileName;
                    startInfo.Arguments = "";
                    Process process = new Process();
                    process.StartInfo = startInfo;
                    process.Start();
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message);
                }
            }
        }

        private void toolStripStatusLabel1_Click(object sender, EventArgs e)
        {

        }


       

     }
}