Why psql can not connect to server?

When I run the command Rails s and refresh http://localhost:3000/ . I get the following error :

Internal Server Error
could not connect to server: No such file or directory Is the server running locally and accepting connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
WEBrick/1.6.0 (Ruby/2.7.1/2020-03-31) at localhost:3000

I have tried every possible solution given on StackOverflow. it isn't working for me .

I am using Rails on Bash in Ubuntu for Windows.Here are the versions : Rails 4.2.10 Ruby 2.7.1p83 railties-4.2.10