XBox won't connect to Live

[PSonic]

Ok, tried to do the Evox install and HD upgrade myself. Big mistake. I won't go into that mess again, but I did attempt to explain what I had done in a few recent posts on this forum. Thanks to the people who replied.

Anyway, after putting my XBox in what I thought to be a FUBAR state, I managed to restore the original C: and E: drives to the original HD. One big problem: XBox Live is still listed on my dash, but it will not allow me to connect. I am running through a Linksys router (which worked fine until I decided to be an idiot and open my XBox).

My gamertag is gone. Not there anymore. Missing. My only options are New Account and Account Recovery. When I test the network settings, I see the following:

Cables connected
IP Settings configured
DNS Resolved
Xbox Live not found.

I called Microsoft and played dumb, which at this point isn't too hard for me. They attempted to blame it on the router, but I know that's not the issue. In their words, they are "escalating" my situation and will get back to me.

I want to somehow be able to recover my gamertag and get back online. Can someone help me out?