Can you tell us what model your router is?
In that case can you go to a machine that can get online through the router then click Start and then Run and in the Run box can you type CMD then hit enter to open a DOS window.
From there can you type ipconfig then hit enter and make a note of the Gateway address which should be something like 192.168.1.1
Once you have that can you open a Internet Explorer Window and type the gateway address in the following format http://192.168.1.1 then hit enter to open the routers login page.
When prompted to login Just click Ok then on the top left go to setup then click wireless settings and browse down to find manual wireless settings.
Once you are there can you seeif it lists your password XXXXX you can write it down and if not can you go ahead and setup a new password, To do this can you scroll down to go to security settings and choose your prefered level of secrity and enter your choice of password XXXXX save your changes and see if you can now get on through your wireless network.
Let me know if you have any issues
Sorry I am missing something, Where are you being asked for the machines PIN?
When I am in D-Link Systems trying to connect my new computer to the wireless network.
I am going to have to opt out and pass you over to another expert as I have never heard of a Dlink router asking for a Pin.
Just sit tight and the new expert will be right with you.