Can you print from any other computer or device? Is it just the windows computer that is having trouble?
connected my Canon MP640 over wifi but I cannot now print from my Windows 7 laptop
How were you connected to the printer when it did work?
What model TC is this?
Is the computer able to fully access internet and the TC hard disk?
If you have a previous wrong configuration of the printer.. delete all traces of it, reboot the laptop and start over.
Find out the IP address of the printer and ping it. To be accessible on the network it must be pingable.