Try a ping sweep on your network:
1) Download any one of a number of free ping sweep tools, this is a decent one:
http://www.netscantools.com/freeware.html
2) With your Pi powered off run the utility and note the IP addresses responding.
3) Power on your Pi, wait 2 minutes.
4) Run the utility again, note any addresses responding now that didn't in #2.
5) Type those addresses in your web browser, see if you can connect to your Pi.
If there's no difference in the hosts responding in #2 and #4 something is amiss with your Pi, it's connection, etc.
Do try a WIRED connection first. Get into the Pi with a wired connection THEN setup the wireless if desired.
Good luck.
