Mobile menu disappeared

A client told me that the menu on the mobile homepage has disappeared (on Android and iPhone). It is still there on the desktop version. As I can't build homepages (I'm quite happy I can keep mine up to date) I looked through the forum, found something about  some code, but I can't find where I should change it or if that is not even the wrong thing. Can anyone of you help me out? Thanks so much in advance! I think it is called the hamburger menu, but that's something I just learned minutes ago 😉

If you use some code affects on mobile, maybe it is problem, what is site url? We can check easier

Sorry, I didn't get a notification. My homepage is www.elisevanes.nl. 

To fix mobile menu on HOMEPAGE, you can add this code to Website Tools (under Not Linked) > Custom CSS

body.homepage div#mobileMenuLink a:before {
    content: "Menu";
}