Unable to connect to docker

When i am executing docker commands
like
docker container ls (or)
docker version in command prompt phasing issue

it says “error during connect: Get http://%2F%2F.%2Fpipe%2Fdocker_engine/v1.40/containers/json: open //./pipe/docker_engine: The system cannot find the file specified. In the default daemon configuration on Windows, the docker client must be run elevated to connect. This error may also indicate that the docker daemon is not running.”

How to resolve this issue??

Source: StackOverflow