Originally Posted by pcou
It's troubleshooting my friend, the DHCP server is what gives you your IP address if you haven't set your computer to run off of a static IP. I had you check another computer simply because if no computer connected was able to access the internet it makes it that much easier to pin down where the problem lies, in which case we've verified its your computer. Is your computer set to use a static IP or DHCP? You can find out by going to network and sharing center > view status (for your local area connection) > click details > click view properties > choose internet protocol version 4 > choose properties > ensure obtain an IP addresss automatically is selected.
If it is, open a cmd prompt and type in
This will release your IP address (which is stuck on 169.x.x.x) and attempt to establish communication with the DHCP server again. My guess is you've tried resetting multiple times with no luck. If this is the case and you still don't get connectivity, in a cmd prompt type in
netsh ip int reset netshlog.txt
This will reset two keys in the registry that TCP/IP uses and log it in netshlog.txt. Essentially it reinstalls the TCP/IP suite, which we're going to assume is corrupted and is preventing you from obtaining an IP address. Reboot and see if you're up and running. If not, then your winsock key may be corrupted. Open cmd prompt and type in
netsh winsock reset
For good measure reboot. This will reset Winsock to it's default state. If memory serves me correct, this will also remove exceptions in window's firewall, but to be honest I use a third party firewall and XP at work so I can't confirm this for sure. You can verify your firewall settings after you run this command through the firewall control panel. If they are removed, you would probably be best off reinstalling the security suite of your choice (your antivirus and malware protection) to ensure you haven't somehow affected their ability to provide protection. You may also need to create exceptions for any programs you use that access the internet (games, instant messengers, etc). Again I'm not a subject matter expert on the inner workings of windows firewall.
If none of the above has you at least able to obtain an IP address, then by all means say so. You may end up having to backup your personal files and doing a clean install. The other immediate things I can think of that may be causing this:
MAC filtering is enabled on your router
Your computer is infected with some sort of malware
Keep me updated.