Next Previous button in GridView Custom Pagination

With reference to

http://www.aspsnippets.com/Articles/Custom-Paging-in-ASP.Net-GridView-using-SQL-Server-Stored-Procedure.aspx

You just need to use the following PopulatePager Method

private void PopulatePager(int recordCount, int currentPage)
    {
        double dblPageCount = (double)((decimal)recordCount / decimal.Parse(ddlPageSize.SelectedValue));
        int pageCount = (int)Math.Ceiling(dblPageCount);
        List<ListItem> pages = new List<ListItem>();
        if (pageCount > 0)
        {
            pages.Add(new ListItem("First", "1", currentPage > 1));
            if (currentPage != 1)
            {
                pages.Add(new ListItem("Previous", (currentPage - 1).ToString()));
            }
            for (int i = 1; i <= pageCount; i++)
            {
                pages.Add(new ListItem(i.ToString(), i.ToString(), i != currentPage));
            }
            if (currentPage != pageCount)
            {
                pages.Add(new ListItem("Next", (currentPage + 1).ToString()));
            }
            pages.Add(new ListItem("Last", pageCount.ToString(), currentPage < pageCount));
        }
        rptPager.DataSource = pages;
        rptPager.DataBind();
    }