Try this it may help you
string connectionString = GetConnectionString();
OleDbConnection connection = new OleDbConnection(connectionString);
connection.Open();
OleDbDataAdapter adapter = new OleDbDataAdapter("SELECT * FROM [Sheet2$]", connection);
DataTable dtImprtExcel = new DataTable();
adapter.Fill(ds);
connection.Close();
after that use the table ds to fill your datatable