I have recently tried to upgrade to the current (as of yesterday) version of the hot pot module. Whilst the upgrade was correctly recognised and seemed to go reasonably well the process crashed when it tried to run the settings screen. At that point I dicovered that all the icons had become corrupt - particularly when the 'turn editting on' option was used. The corrupton semed to be restricted to that one session as other users did not have the same problem. I then tried removing the hot pot module and re-installing it. At that point it seemed to work ok but again the icons were corrupted for that session. As re-instaling the module removed all the existing hot potatoes from our server I reset it back to before I had started. I was just wondering if this corruption had happened with others and if it was serious enough to not contionue wih the install. As far as I could tell all the hot potatoe exercises were working fine.
If your icons are missing, I suggest you clear your browser cache, and at the same time purge the Moodle caches (Settings -> Develeoper -> Purge all caches). I do not think the HotPot activities were removed from your server. It is just that you cannot see them if the HotPot is not installed or it is installed but not enabled. I suggest you proceed with updating the HotPot module. The latest version contains some important and useful improvements.
I did this and the icons are still missing.
Can you see the icons, if you switch to the standard theme?
Can you see the icons if you access the Moodle site from another computer?