Microsoft Office Access Database Engine error - URGENT

Question

Hi all,
I am getting the error -

The Microsoft Office Access database engine cannot open or write to the file ''. It is already opened exclusively by another user, or you need permission to view and write its data.

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I want to update the excel sheet records to sql server table from front-end.
--
My method is-
--------------
#region ExcelSheetNames
  private string[] GetExcelSheetNames(string excelFile)
  {
  OleDbConnection objConn = null;
  System.Data.DataTable dt = null;
  try
  {
 
  //String connString = "Provider=Microsoft.Jet.OLEDB.4.0;" +
  //  "Data Source=" + excelFile + ";Extended Properties=Excel 8.0;";
  String connString = ConfigurationManager.ConnectionStrings["Excel07ConString"].ConnectionString;
  // Create connection object by using the preceding connection string. 
  objConn = new OleDbConnection(connString);
  // Open connection with the database.
  objConn.Open();
  dt = objConn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
  if (dt == null)
  {
  return null;
  }
  else
  {
  String[] excelSheets = new String[dt.Rows.Count];
  int i = 0;

  // Add the sheet name to the string array.
  foreach (DataRow row in dt.Rows)
  {
  excelSheets[i] = row["TABLE_NAME"].ToString();
  i++;
  }
  return excelSheets;

  }

  }
  catch (Exception err) { err.Message.ToString(); return null; }
  finally
  {
  // Clean up.
  if (objConn != null)
  {
  objConn.Close();
  objConn.Dispose();
  }
  if (dt != null)
  {
  dt.Dispose();
  }
  }
  }
  #endregion
#region GetExcelSheets
  private void GetExcelSheets(string FilePath, string Extension, string isHDR)
  {
  try
  {
  System.Diagnostics.Process.Start("");
  string conStr = String.Empty;
  switch (Extension)
  {
  case ".xls": //Excel 97-03
  conStr = ConfigurationManager.ConnectionStrings["Excel03ConString"].ConnectionString;
  break;

  case ".xlsx": //Excel 07
  conStr = ConfigurationManager.ConnectionStrings["Excel07ConString"].ConnectionString;
  break;

  }
  //Get the Sheets in Excel WorkBoo
  conStr = String.Format(conStr, FilePath, isHDR);
  OleDbConnection connExcel = new OleDbConnection(conStr);
  OleDbCommand cmdExcel = new OleDbCommand();
  OleDbDataAdapter oda = new OleDbDataAdapter();
  cmdExcel.Connection = connExcel;
  connExcel.Open();
  //ddl_excelsheets
  ddl_excelsheets.Items.Clear();

  //ddl_excelsheets.Items.Add(new ListItem("--Select Sheet--", ""));
  //ddl_excelsheets.DataSource = connExcel.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
  //ddl_excelsheets.DataTextField = "tbl_AssetDetails";
  //ddl_excelsheets.DataValueField = "tbl_AssetDetails";
  //ddl_excelsheets.DataBind();

  ddl_excelsheets.Items.Add(new ListItem("--Select Sheet--", ""));
  ddl_excelsheets.DataSource = connExcel.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
  ddl_excelsheets.DataTextField = "TableName";
  ddl_excelsheets.DataValueField = "TableName";
  ddl_excelsheets.DataBind();

  connExcel.Close();
  }
  catch (Exception err) { err.Message.ToString(); }
  }
  #endregion
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Please let me know where I am going wrong.