reinstall mongodb

# attention: this will delete all databases and everything mongodb related
# intended to fix a not starting mongoDb installation on ubuntu > 18.04

sudo apt purge mongodb-org*
sudo rm -r /var/log/mongodb
sudo rm -r /var/lib/mongodb
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv EA312927
echo "deb http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/3.2 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-3.2.list
sudo apt update
sudo apt-get install -y mongodb-org