Try resetting your registry for SolidWorks. You will lose all your other personal settings but should get your menu back. Try using the "Copy Settings Wizard" before resetting the registry & then restore settings after resetting registry. Hopefully this will retain all your other personal settings but not bring but the menu issue.
Follow instructions on the folowing posts:
Saved his settings, reset registry, restored settings...no joy. So could be the settings file. Why? Who knows; corrupt maybe.
Reset registry, copied over a known good settings file. Opened SW, success.
We try to keep Std settings & customization to a minimum here. It's just another element requiring debugging when there's an issue.
Almost a happy user!