Menu not opening on mobile site

On the mobile version on my site the drop down navigation menu won’t open, it highlights when you click it like it would if it was going to open but never does. I have checked in my menu settings and viewed from mobile view and it shows it as working, it works on desktop and tablet just not on mobile as of the past couple of days. My WordPress is up to date as are all of my plug-ins. Obviously this is a big issue I need to resolve quickly as no one can access anything on my site. I have looked into the issue a bit and what I’ve tried hasn’t fixed the issue. I’m not very experienced as I “inherited” maintenance of this website recently but I have managed until now, I can’t seem to find the fix to this problem. I know my theme can affect this, I’m using theme “Twenty Seventeen” but not sure if it is causing the issue or not because this is the theme I’ve always had. Need help! Thanks.