Remove all the connections and start over? I'm not on my Vista laptop so I can't offer any step by step but you can dive into the networking areas to remove the now failed connection, make a new one.
I also will make the assumption you use our suggestions in the forum sticky so I will not duplicate those here.
I have a cable modem wired to a linksys router that is wired to an apple airport. My ibook G4 finds the internet without an issue also my iPhone finds the internet without an issue, and the Dell used to find the internet most of the time, but now I seem to be unable to get the Dell to connect to the internet. It tells me I have local only access. I've also done a restore to the date of service when I did have access to the internet and it still said I have local only access. In addition, I've read through many posts on this issue and have also modified the register as recommened in some posts from the Microsoft fix page, and rebooted and I still can't get beyond the local only access with the Dell. This is a relatively new Dell. Unfortunatley I bought the Dell earlier this year when they only offered Vista - they would not sell me the XP OS. Please help.