wordpress menu link Forbidden You don't have permission to access /index.php on this server.

After getting the above issue the answer for me was as simple as this.

> I went to Settings > Permalink Settings

and click on 'Default' instead. 

>  then I checked the website and my menu links worked fine.

> on going back to > Settings >Permalink Settings  > Common Settings

and reset the selection to 'Post Name'  and by some sort of miracle the menu's work again. :)