how do i connect to the router via cable??

ive been told to solve my network key problem i need to connect to the router via the cable then disable the security or change the WEP key

could someone give me a step by step basic guide to doing this as im a total novice with the wireless system

The Links I gave you yesterday gave you the location of the user manual.
It would give you all the necessary information you require.
If someone has accessed your router and changed it's settings they may have changed the admin password as well so will need to reset the TL-WR641G first(see manual).
You connect the ethernet socket on your computer to one of the LAN ports on the router to access it via "wire".

yea i opened them but as i say im very novice at anything n basically need it in fools english step by step how to do it as the user manual is quite confusing. ive got the pc attached via the wire but dont know how to access the router from here
ive tried accessing it as it says by typing http://192.168.1.1 into my web browser but it just tells me connection timed out. is this cuz im using firefox not IE or netscape?

Since whoever altered your security settings may have changed others it is best to start afresh.
1.Re-set your router to factory defaults using the reset button page5 of manual.
2.If you look at annex B of the manual it tells you how to set up the TCP/IP settings for your Ethernet card to give either IP address automatically or a static IP. Try auto first.
3. Open your web browser and see if you can access 192.168.1.1.
If you can't try using a static IP of 192.168.1.2 with subnet mask 255.255.255.0.