Hi Sterling,
Many thanks for taking the time to reply to me. Unfortunately I am still struggling to get this working.
When i open Airport Utility, it says 'No configured AirPort base stations have been found. Airport Utility will continue searching'. Therefore I am not able to do the actions you propose above.
So I then decided to click the reset button on the back of the unit. Once I have done this then it does find the Extreme.
So then I follow the steps to reconnect by entering my password, I skip the next part where it is requesting 'Provide the PPPoE connection information you received from your ISP: Account Name / Password / Service Name / Connection' as I have no idea what this is talking about (is this where I am going wrong?).
Then after a lot of wheel spinning it comes up with the message 'An unexpected error occured. Try again.' But there is no help telling me what that error was... It then loses the connection and is no longer visible in Airport Utility and I need to click the reset button on the back of the unit for it to find it again. I've done this several times this evening with the same result each time.
Any ideas?
Thanks for your patience!