|Is this a wireless connection problem? Does the laptop detect an available wireless network and simply fail to connect to it?|
What kind of security protocol is in force on the wireless router? Do you have access to the router's admin interface from another (wired) PC?
You really haven't given sufficient information about your system or internet connection to isolate your problem.
Is this a new system trying to connect for the first time? Did it work previously and suddenly will no longer connect?
Goin' Fishin' (Some day)