My server hosting ability has gone sterile?

[Box29]

Alright, just so you know I run windows xp, and I have been using the simple half life and source dedicated server client from the steam list to host simple games on my computer for my friends and I. I have been doing this for two years without problem after one of my friends set up the port stuff. I came on last week to try and host a server, but for some reason, now it is not possible? I have no idea what could be wrong, please, anyone, HELP!!! I just don't see why I've been able to do this for two years, and then all of a sudden, without making any changes on my part, my ability to host servers is gone... The client starts up and says it's up, but my server does not show up in any server list nor does ANY ip I try work to connect to it. Is there any information I can provide that helps?

[Drocona]

If it doesnt show anywhere it's most probably a port problem. Maybe your router has been reset (can be from unplugging it once). Check the port forwarding, see if it's still correct. (if you dont know how, http://www.portforward.com or just search these forums for more information, there are loads of posts about it)