...
I was wondering , is it possible for anyone to use the nick which is password protected?
...
Sure. It depends on
how it is protected.
Sometimes users get the mistaken idea that simply registering their nick protects it from being used by anyone else. This is not true. There is another step, if one desires to enable it.
To get more info on how to have NickServ
automatically kill the use of your nick - that is: force a nick change on anybody that uses your nick - type this and NickServ will respond with explanation and instructions:
/msg nickserv help set kill
and note the switches: {ON | QUICK | IMMED | OFF}
and their explanations.
(Avoid using the "Immed" switch - it actually sounds impossible to use. )
From your question, it sounds like you might like to use the basic "On".
But before you do, you might like to examine some other functions of NickServ.
First, the Recover command. Type this in an IRC chat, to get Nickserv to respond with instructions and an explanation:
/msg nickserv help recover
Since your nickname is registered, you could use the Recover command to bump off anyone that is using your nick, if they are there when you arrive. (You can do this right now, with no further configuring of Nickserv options.)
Whereas if you set the Kill option, whether you are there or not - Nickserv will force them off. But Nickserv would force YOU off too, if ever you forget to identify with Nickserv.
If ever you use the Recover command, you will have to wait one minute before even you can begin to use your own nick.... or, you can send the Release command. Type this to get more information on how to use the Release command:
/msg nickserv help release
'See' you around.