Well adding random JS is not the way to fix your problem. Without seeing your website or .bsdesign file, there’s little chance anyone here will be able to solve your problem. There are countless things that could have caused this. You may have found a bug in the software, or you’ve done something to your code to cause the dropdown to stop working.
The standard way to diagnose such problems is to work backwards. Assuming you’re backing up your site (you ARE backing up your site, right?) at some point I presume the Menu worked. So go back to the last version it was working, open it, and do a side-by-side comparison to the one that’s not working. Then start disabling the additions on the non-functional website one-by-one. Eventually you should find the culprit.
Another test is to just add a second navbar to the page, and see if that has the same problem. If not, you’ve got a code issue specific to just your first Navbar. If it affects both, it could also be a code issue, but something universal.
What happens if you start a new file from scratch and add a Navbar? Does the dropdown work? What happens if you start a new file and copy/paste the Navbar that’s not working into the new, blank website.
You’ve got to be like Sherlock Holmes when it comes to this stuff. Process of elimination. Just keep looking, disabling, until you figure out where things went haywire.