This is quite a common problem so as it comes up frequently, I decided that the best solution would be to write up a post on how to fix it.

You are in the situation where you have modified your site, or recently upgraded and all of a sudden the dropdown menus stop working. Often this is just in some threads, and more often than not it is the thread tools menu that you notice is not working.

Despite the fact that it only seems to be the dropdowns in the threads themselves that are not working, the fault is usually with the navbar template.

The best way to fix it is to revert your navbar template. However, if you are running a custom style, it is advisable to first export your style in case additional modifications to it have been made.

If your navbar has been moved to your header, then you will also need to remove it from there.

When you have got just a default navbar running, with no navbar in your header (if appropraite) then try the thread tools menus again. in the majority of cases they will now work.

Once you have it working, add each link back to your navbar, checking between each one that the thread tools and other dropdowns are still working. Take your time while doing this, as any errors will break them again.

If, after reverting your navbar, your menus still do not work, and you have made any modifications to your showthread template, then it is also recommended that you revert this template. In the majority of cases this is not required.

While having your navbar in your header can look good depending on your style, it can in some instances, if not coded correctly, cause these problems. A good solution to this is to move the nav buttons part of your navbar to the top of your navbar template underneath the script for the logout button then add a couple of breaks to space it out.

I hope that you find this useful.