Yesterday I experimented briefly with a new theme for my site. Unfortunately it clobbered my sidebar, and when I restored my usual theme most of the widgets there were destroyed.
I’ve managed to resurrect the ones that were most important to me, but caching issues may cause your sidebar to look wonky for a while. Depending on your browser you may or may not have a keystroke combination available to you to force-reload my site and ignore any bits left in your cache. All browsers (I believe) provide a menu option to clear browsing data, which is more drastic, but would clear your cache.
As for the theme, it’s been deleted from my server, never to return again.