Computer not getting internet access though wifi?

[Kiroro N]

I have a friend whose computer has suddenly decided that it's not going to agree with any wifi connections. The computer will connect to wifi, but she cannot get online because there's not internet access.

She said that the issue did not occur after the computer automatically updated; she just came home from work one day and was unable to get internet access.

This problem occurs in all the areas she has tried getting wireless internet access from, not just in her own home.

She has tried resetting her router.

Her computer is a Compaq with Windows 7 Home Premium.
EDIT: Also, neither of us are techies, so in regards to those DHCP tips, could you provide some instructions that are easy to follow? We both read that and it might as well have been French...