I've had several problems with the theme (k2 sandbox) dropping from my installation. All of the files are there and nothing has changed, but nothing shows on the site and the theme is no longer recognized in the wordpress presentation tab. Seems to happen sporadically. I tried deleting the remaining themes, that it would default to once dropping the theme and that did not fix. It has happened three time in a month and then mysteriously returns, wordpress recognizes it, and it shows up in the presentation menu.
It sometimes occurs after editing the css, but I will revert to previous version of style.css and it won't fix.
Any help is greatly appreciated!