DOCKER_HOST Couldn't connect to Docker daemon at http+docker://localhost - is it running? code example

Example 1: ERROR: Couldn't connect to Docker daemon at http+docker://localhost - is it running?

open the terminal and type sudo dockerd and leave it open
open new terminal and type sudo docker-compose up -d or sudo docker-compose build

Example 2: Couldn't connect to Docker daemon at http+docker://localhost

sudo usermod -aG docker $USER
sudo chown $USER /var/run/docker.sock