Hi,
I guess OnPageIndexChanging event is missing in your grid view defination.
Use the below code:
<asp:GridView ID="grdView" runat="server" AutoGenerateColumns="False"
AllowPaging="True" AllowSorting="True" onrowediting="grdView_RowEditing"
onrowcancelingedit="grdView_RowCancelingEdit"
onrowupdating="grdView_RowUpdating" EnableModelValidation="False"
OnPageIndexChanging="gridView_PageIndexChanging" >
Also,
Save the dataset in a session variable say Session["gridrows"].
And ,in the gridView_PageIndexChanging method, write the code for
gridView.PageIndex = e.NewPageIndex;
griddview.DataSource = (DataSet)Session["gridrows"];
griddview.DataBind();
Hope this helps.