convert loop to linq

Question

How to convert foreach loop in linq there is any esay way to change loop to linq i have some code showen blewo

static public string table2Json(DataSet ds, int table_no)
{

    try
    {
        object[][] tb = new object[ds.Tables[table_no].Rows.Count][];

        int r = 0;
        foreach (DataRow dr in ds.Tables[table_no].Rows)
        {
            tb[r] = new object[ds.Tables[table_no].Columns.Count];
            int col = 0;

            foreach (DataColumn column in ds.Tables[table_no].Columns)
            {
                tb[r][col] = dr[col];
                if ((tb[r][col]).Equals(System.DBNull.Value))
                {
                    tb[r][col] = "";
                }
                col++;
            }
            r++;
        }
       string table = JsonConvert.SerializeObject(tb, Formatting.Indented);
        return table;
    }
    catch (Exception ex)
    {
        tools.log(ex.Message);
        throw ex;
    }
}