You might try re-entering manual set up. Right click connection manger
and edit connections. Set up a new wired connection and name it "Auto
eth0 " without parenthesis. The name of your network goes at SSID. If
you have security set up as WEP or WPA and so on - type in the pass
phrase (security key) on the next tab. Choose the appropriate security
level WEP WPA or None. It should automatically connect within a second
or two or simply reboot and it should automatically connect at start up.

The other suggestion was to re-insert your Linux CD to run it as Demo
(Live Distro CD) and not reinstall. In the Live Distro Demo - it
automatically connects to broadband/dsl - ethernet cable from your
broadband/dsl modem to ethernet connection on computer - or from the
Router out ehternet wired connection as opposed to using wireless. There
should be at least one or two of these ethernet cable ports on the
router and you must have your broadband/dsl modem plugged into the
Router at the appropriate port (modem port - from modem to router). This
is a good trouble shooter and quick enough to see if anything else is
damaged. In other words rule out. See what is working and what is not
easily.

Did it work ? Do you have a second pc to try connections ?