Hi @ANDREA 

i AM USING THE SAME APPROAH BUT THE VALUE FEATCHED IN e.Row.Cells(4) is coming as nothing/Empty

My gridview is as follows

<asp:GridView ID="Empdata" runat="server" AutoGenerateColumns="false" Font-Names="Arial"
    Font-Size="11px" HeaderStyle-BackColor="DarkOliveGreen" ShowFooter="true" AllowPaging="True"
    OnPageIndexChanging="OnPaging" OnRowCancelingEdit="CancelEdit" OnRowEditing="EditRecord"
    OnRowUpdating="UpdateRecord" PageSize="20" HeaderStyle-HorizontalAlign="Center"
    HorizontalAlign="Center" OnRowDataBound="OnRowDataBound">
    <Columns>
        <asp:TemplateField ItemStyle-Width="35px" HeaderText="Emp ID">
            <ItemTemplate>
                <asp:Label ID="lbEmpID" runat="server" Text='<%# Eval("EmpID")%>'></asp:Label>
            </ItemTemplate>
            <EditItemTemplate>
                <asp:TextBox ID="txtEmpID" runat="server" Text='<%# Eval("EmpID")%>'></asp:TextBox>
            </EditItemTemplate>
            <FooterTemplate>
                <asp:TextBox ID="txtEmpID" Width="35px" runat="server"></asp:TextBox>
            </FooterTemplate>
        </asp:TemplateField>
        <asp:TemplateField ItemStyle-Width="35px" HeaderText="EmpName">
            <ItemTemplate>
                <asp:Label ID="lbEmpName" runat="server" Text='<%# Eval("EmpName")%>'></asp:Label>
            </ItemTemplate>
            <EditItemTemplate>
                <asp:TextBox ID="txtEmpName" runat="server" Text='<%# Eval("EmpName")%>'></asp:TextBox>
            </EditItemTemplate>
            <FooterTemplate>
                <asp:TextBox ID="txtEmpName" Width="35px" runat="server"></asp:TextBox>
            </FooterTemplate>
        </asp:TemplateField>
        <asp:TemplateField ItemStyle-Width="25px" HeaderText="Designation">
            <ItemTemplate>
                <asp:Label ID="lblDesignation" runat="server" Text='<%# Eval("Designation")%>'></asp:Label>
            </ItemTemplate>
            <EditItemTemplate>
                <asp:TextBox ID="txtDesignation" runat="server" Text='<%# Eval("Designation")%>'></asp:TextBox>
            </EditItemTemplate>
            <FooterTemplate>
                <asp:TextBox ID="txtDesignation" runat="server"></asp:TextBox>
            </FooterTemplate>
        </asp:TemplateField>
        <asp:TemplateField ItemStyle-Width="25px" HeaderText="Date Of Joining">
            <ItemTemplate>
                <asp:Label ID="lblDateOfJoining" runat="server" Text='<%# Eval("DateOfJoining","{0:dd MMM yyyy}")%>'></asp:Label>
            </ItemTemplate>
            <EditItemTemplate>
                <asp:TextBox ID="txtDateOfJoining" runat="server" Text='<%# Eval("DateOfJoining","{0:dd MMM yyyy}")%>'></asp:TextBox>
            </EditItemTemplate>
            <FooterTemplate>
                <asp:TextBox ID="txtDateOfJoining" runat="server"></asp:TextBox>
            </FooterTemplate>
        </asp:TemplateField>
        <asp:TemplateField ItemStyle-Width="25px" HeaderText="Salary">
            <ItemTemplate>
                <asp:Label ID="lblSalary" runat="server" Text='<%# Eval("Salary")%>'></asp:Label>
            </ItemTemplate>
            <EditItemTemplate>
                <asp:TextBox ID="txtSalary" runat="server" Text='<%# Eval("Salary")%>'></asp:TextBox>
            </EditItemTemplate>
            <FooterTemplate>
                <asp:TextBox ID="txtSalary" runat="server"></asp:TextBox>
            </FooterTemplate>
        </asp:TemplateField>
        <asp:TemplateField ItemStyle-Width="25px" HeaderText="Department">
            <ItemTemplate>
                <asp:Label ID="lblDepartment" runat="server" Text='<%# Eval("Department")%>'></asp:Label>
            </ItemTemplate>
            <EditItemTemplate>
                <asp:TextBox ID="txtDepartment" runat="server" Text='<%# Eval("Department")%>'></asp:TextBox>
            </EditItemTemplate>
            <FooterTemplate>
                <asp:TextBox ID="txtDepartment" runat="server"></asp:TextBox>
            </FooterTemplate>
        </asp:TemplateField>
        <asp:TemplateField>
            <ItemTemplate>
                <asp:LinkButton ID="lnkRemove" runat="server" CommandArgument='<%# Eval("EmpID")%>'
                    OnClientClick="return confirm('Do you want to delete?')" Text="Delete" OnClick="DeleteRecord"></asp:LinkButton>
            </ItemTemplate>
            <FooterTemplate>
                <asp:Button ID="btnAdd" runat="server" Text="Add" OnClick="AddNewRecord" />
            </FooterTemplate>
        </asp:TemplateField>
        <asp:CommandField ShowEditButton="True" />
    </Columns>
</asp:GridView>

And the function im using for changing background color of cell is as below

Protected Sub OnRowDataBound(sender As Object, e As GridViewRowEventArgs)
   If e.Row.RowType = DataControlRowType.DataRow Then
       Dim cell As TableCell = e.Row.Cells(4)
       Dim quantity As String = (cell.Text).ToString

       If quantity < "10000" Then
            cell.BackColor = Color.Red
       End If
       If quantity >= "10000" AndAlso quantity < "50000" Then
            cell.BackColor = Color.Yellow
       End If
       If quantity >= "50000" Then
            cell.BackColor = Color.Orange
       End If
   End If

End Sub

Hi asitmisra,

Refer the below article.

Dynamically change GridView Cell Background Color based on condition in ASP.Net using C# and VB.Net

Try this

 Protected Sub OnRowDataBound(sender As Object, e As System.Web.UI.WebControls.GridViewRowEventArgs)

        If e.Row.RowType = DataControlRowType.DataRow Then
            
            Dim cell As TableCell = e.Row.Cells(4)
            Dim quantity As Integer = DirectCast(e.Row.FindControl("lblSalary"), Label).Text

            If quantity < 10000 Then
                cell.BackColor = Color.Red
            End If
            If quantity >= 10000 AndAlso quantity < 50000 Then
                cell.BackColor = Color.Yellow
            End If
            If quantity >= 50000 Then
                cell.BackColor = Color.Orange
            End If
        End If

    End Sub

here muddassar ahmed khan is bound field and i m using Template field in gridview doing it that way generates a system format exception and gives and empty value in the field quantity