Sounds to me like your computer was making some changes to the file system when the power went out. If these were critical files being changed, the system may have noticed file corruption when you turned it back on after the outage and it may have reset your gnome back to factory defaults. This might explain why your files are still there, but any/all custom settings are gone (like you said with chrome, its as if you just installed it).
Unfortunately, there is no "system restore" or "time machine" for ubuntu (at least nothing comes stock with it). There are 3rd party programs like Timeshift that were made for this exact reason, rolling back system changes whenever necessary.