Hey Guys,
Don't need help but I thought I'd post for posterity. I've had plenty of times that my Raspberry Pi has powered off due to power outages or crashes, etc, then receive the "OctorPrint server is currently not running" error.
As a standard now, I run the following commands from SSH to reinstall python, regenerate the octoprint virtualenv and reinstall octoprint, all without having to reimage the sd card.;
sudo apt-get install --reinstall python-virtualenv/oldstable
sudo apt-get install --reinstall python2.7/oldstable libpython2.7/oldstable
rm -rf /home/pi/oprint.last
mv /home/pi/oprint /home/pi/oprint.last
rm -rf /home/pi/.cache
virtualenv oprint -p python2
source oprint/bin/activate
pip install https://get.octoprint.org/latest
pip install --upgrade --no-cache https://get.octoprint.org/latest
sudo reboot
Once the python 3 version is in stable release, you can omit the "-p python2" from the virtualenv command, and probably exclude reinstalling python 2.7 from oldstable.