Just recently my iPod Touch has lost contact with the internet. The wi-fi symbol shows a connection and in the settings it shows my home network, but none of the apps which require internet access will work. I have done all the usual things such as turning the wi-fi off and on an restoring the setting in iTunes. However nothing seems to work. An interesting point which I don't know whether this is normal or not, in the wi-fi settings, under the DHCP tab, the ip address bears no relation to any of the other ip addresses allocated by my router to other computers on the network.
My guess is your router is set as a DHCP server (so it assigns the IP addresses) but the iPod hasn't found it. It will then assign itself an address starting 169 instead of your router's (likely) 192 series. You could try telling the iPod to forget your network then enter the settings again. You haven't by any chance altered anything in the router - turned on MAC address filtering perhaps?
When I went to the Bournemouth meeting yesterday I asked one of the staff at Solutions to see if my iPod would connect with their network; it did, so the problem was not in the ipod. I had done all the checks that Mick suggested plus a complete restore, so when I returned home from the meeting I resorted to old fashioned technology and turned my router off and left it off all night. When I turned it on again this morning the ipod connected without a hitch. Which only goes to show that some of the old tricks still work.
The thing that had confused me initially was that both my iMac and Macbook would connect wirelessly through the router all the time, it was just the iPod that had a problem and this had happened spontaneously without any alteration to the router other than to make it visible so my son could connect his iPhone, which connected perfectly.
Lionel Ogden 