how to restore the database in ms accessby using c# windows application

Error   1 ; System.Linq.Strings' is inaccessible due to its protection level   C:\Users\WinBilling\Documents\Visual Studio 2008\Projects\WindowsFormsApplication1\WindowsFormsApplication1\Form1.cs    62  64  WindowsFormsApplication1

private void ButtonRestoreBackup_Click(object sender, EventArgs e)
       {
           try
           {
               OpenFileDialog dlg = new OpenFileDialog();
               dlg.Filter = "Microsoft Access Database(2002-2003) (*.mdb)|*.mdb|Microsoft Access Database(2007-2009) (*.accdb)|*.accdb";
               // If you want to keep default extensiion *.mdb then FilterIndex = 1 or if you want to keep default extension *.accdb then FilterIndex=2
               dlg.FilterIndex = 1;

               if (dlg.ShowDialog() == System.Windows.Forms.DialogResult.OK)
               {
                   TextBoxRestoreBackup.Text = dlg.FileName;
               }
           }
           catch (Exception ex)
           {
               MessageBox.Show(ex.Message);
           }
       }

       private void ButtonRestoreDestination_Click(object sender, EventArgs e)
       {
           try
           {
               FolderBrowserDialog folder = new FolderBrowserDialog();
               if (folder.ShowDialog() == System.Windows.Forms.DialogResult.OK)
               {
                   TextBoxRestoreDestination.Text = folder.SelectedPath;
               }
           }
           catch (Exception ex)
           {
               MessageBox.Show(ex.Message);
           }
       }

       private void ButtonRestore_Click(object sender, EventArgs e)
       {
           try
           {
               DialogResult result = MessageBox.Show("Do you want to restore the Database?", "Do you?", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
               string fileName = null;
               //fileName = (TextBoxRestoreBackup.Text.ToString()); //.Substring(Strings.InStrRev(TextBoxRestoreBackup.Text, "\\"));
               fileName = TextBoxRestoreBackup.Text.Substring(Strings.InStrRev(TextBoxRestoreBackup.Text, "\\"));

               if (result == System.Windows.Forms.DialogResult.Yes)
               {
                   if (System.IO.File.Exists(TextBoxRestoreDestination.Text + "\\" + fileName))
                   {
                       DialogResult resultReplace = MessageBox.Show("This File is already exist. Do you want to replace the Database?", "Do you?", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
                       if (resultReplace == System.Windows.Forms.DialogResult.Yes)
                       {
                           System.IO.File.Delete(TextBoxRestoreDestination.Text + "\\" + fileName);
                           System.IO.File.Copy(TextBoxRestoreBackup.Text, TextBoxRestoreDestination.Text + "\\" + fileName);
                       }
                   }
                   else
                   {
                       System.IO.File.Copy(TextBoxRestoreBackup.Text, TextBoxRestoreDestination.Text + "\\" + fileName);
                   }
               }
           }
           catch (Exception ex)
           {
               MessageBox.Show(ex.Message);
           }
       }