Question

How can i get current MainNavigationMenu hyprelink in code behind and check if is current menu clicked then i will change him default CSS.

I try with this code but is always null

HyperLink mainNavigationMenu = siteMapAsBulletedList.FindControl("MainNavigationMenu") as HyperLink;

full repeater code:

<asp:Repeater runat="server" ID="siteMapAsBulletedList" DataSourceID="smdsMenu">
                        <HeaderTemplate>
                            <li><asp:HyperLink ID="MainNavigationMenu" runat="server" NavigateUrl='<%#SiteMap.RootNode.Url%>'
                                Text='<%#SiteMap.RootNode.Title%>'></asp:HyperLink></li>                        
                        </HeaderTemplate>
                        <ItemTemplate>
                            <li><asp:HyperLink ID="HyperLink1" runat="server" NavigateUrl='<%#Eval("Url")%>' Text='<%#Eval("Title")%>'></asp:HyperLink></li>
                        </ItemTemplate>
                        </asp:Repeater>

Answer 1

Are you verifying which type of repeater item you are looking at ?

Attach an ItemDataBound to your repeater and do something like this :

private void rptPanier_ItemDataBound(Object sender , RepeaterItemEventArgs e) 
{
    if (e.Item.ItemType == ListItemType.Header)
    {
      var myItem = (Hyperlink)e.Item.FindControl("YourControlName");
    }
}

Then you will have a reference on it and you can do whatever you want !
Beware tho, the ItemData item, which can be found in the repeateritemeventargs, is always null when the repeater is creating the header.

Hope this helps !