Lost Network key

i have a TP-Link TL-WR641G Wireless router and when im trying to connect to the internet using it its asking for a Network Key or WPA key.

Where do i find this?
ive had the router about 2 years and its never asked for this before and i no longer have the box it came in!

If you have been running an open network then it's possible someone has logged onto your router and changed it's settings.

You don't say which version of the router you have but you can download the manual and latest firmware here:-
TP-LINK Download

The manual will explain how to reset the router to it's default state and how to set up WPA encryption

hiya
thanx

i clicked the link but its telling me

I seem to be having problems with links since I joined this forum.
Try:-
V1
TP-LINK Download
V2
TP-LINK Download
V3
TP-LINK Download

If these fail try:-
TP-LINK Download
Pick the TL-641G from the wireless LAN page