There are two solutions :
1. If you simply can’t connect to docker, it may be the problem of port :
can be solved by the following methods: restart the service:

cd "C:\Program Files\Docker\Docker"
DockerCli.exe -SwitchDaemon

2. If it is a certificate problem, try the following methods to restart the computer:

//Step 1
docker-machine --debug regenerate-certs -f default
//Step 2
docker-machine --debug env default
//Step 3
docker-machine start
//Step 4
docker-machine -D ssh default

Note: If you install Win10 Professional Docker without Docker-Macheine, you can download and install it