Docker file contains the following command
FROM nginx
COPY . /usr/share/nginx/html
To build my docker image i have used following command
docker build -t <tagName>/img .
To run the docker image
docker run -p 80:8080 <tagName>/img
But i am not able to lanch my static site in my browser . i am getting
This site can’t be reached
localhost refused to connect.

You are mapping port 80 to 8080 here:
docker run -p 80:8080 <tagName>/img, so to access your app just use the address: 'localhost:80' (or you can ommit the port since 80 is the default port used in browsers)