Are you running windows 10? There seems to be a problem there. This thread has a suggestion (but note you need to save the directories as it will delete all you work!) on how to clear the data directories which may restore it. I'm starting to wonder if a Win10 update has broken something on Win10.
also note Old_Grey's suggestion on AV perhaps eating files. I assume that search did work for you before something happened (which points at corruption in the temp directories)?
