how do i ping

when your internet cable is unplug or when your internet connecion is crashed

You lose connection to the server.
Correct me if I'm wrong.

That's a ping timeout. When you "ping someone" you can describe it like this: You send a question and recieve an answer. Then you can see the time it took.
If it takes too long because your connection is bad you get a ping timeout so you know what is wrong.

If your internet got connected, "/me disconnected from the game" will show up.

ooh, and ping time is?

window key + r
type "cmd" and press enter
type "ping <address>" eg "ping google.com"
press enter