Hi
Not sure if you sorted this yet but sounds like one of a couple of things.
1. the router isn't assigning IP addresses. Reset the device by powering off/on
2. the router isn't set to assign addresses. you'll need to enter the web configuration page (unlikely to be this unless you changed)
3. computer has a "static" Ip address configured. GO to network connections in control panel , and on both Wireless Connection & Local Area COnnection - Right click, go to properties and on main window double click the TCP(internet protocol) line. Ensure that the option is set to "obtain an IP address automatically".
4. Wireless security is wrong and not connecting (although you say it happens on wired too?)
5. Software problem. Could be lots. Try the steps above first.
Hope it helps
Chris