string connstr = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source =" + vstr + ";Extended Properties='Excel 8.0;HDR=NO;IMEX=1'";
OleDbConnection myConnection = new OleDbConnection(connstr);
myConnection.Open();
DataTable dt = myConnection.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
string tableName = dt.Rows[0][2].ToString().Trim();
string sql = "select * from [" + tableName + "]";
OleDbCommand olecomm = new OleDbCommand(sql, new OleDbConnection(connstr));
OleDbDataAdapter oleadapter = new OleDbDataAdapter(olecomm);
DataSet ds = new DataSet();
oleadapter.Fill(ds, "Sheet1");
myConnection.Close();