Try Ctrl-B - this should toggle the Bookmarks panel.

Also try F11 - this switches to full screen (no top or bottom panels) & back.

Those 2 just affect the display. To get at the menu items, use ALT+ F (file), V (view), B (bookmarks). They should give you the submenus.

Depending on which of the above work, we'll know whether it's a view problem or something odd.

Phil