private void SetLinkButton()
    {
        btnFirst.Enabled = true;
        btnPrev.Enabled = true;
        btnNext.Enabled = true;
        btnLast.Enabled = true;

        if (txtPageIndex.Text == "1")
        {
            btnFirst.Enabled = false;
            btnPrev.Enabled = false;
        }
        Maticsoft.BLL.Products pBll = new Maticsoft.BLL.Products();
        if (txtPageIndex.Text == pBll.GetPagedListCount(int.Parse(txtPageSize.Text), string.Empty).ToString())
        {
            btnNext.Enabled = false;
            btnLast.Enabled = false;
        }
    }

------解决方案--------------------

给你一段代码自己模仿改一下。
public void dataBindhypertensionhome()
       {
           PagedDataSource pds = new PagedDataSource();
           pds.DataSource = B_hypertension.getHypertensionhome();

           pds.AllowPaging = true;
           pds.PageSize = 1;
           int currentIndex = Convert.ToInt32(this.lbl_currentpage.Text) - 1;

           pds.CurrentPageIndex = currentIndex;
           if (currentIndex == 0)
           {

               this.lbt_previouspage.Enabled = false;

           }
           else
           {
               this.lbt_previouspage.Enabled = true;

           }
           if (currentIndex == pds.PageCount - 1)
           {

               this.lbt_nextpage.Enabled = false;

           }
           else
           {
               this.lbt_nextpage.Enabled = true;
           }


           this.lbl_totalpage.Text = pds.PageCount.ToString();

           this.DataList1.DataSource = pds;
           this.DataList1.DataBind();
       }