Windows7 can't connect to any network

Question

Today I've installed some updates from Windows Update and installed SAP client. Then I've rebooted my machine.

After that I was unable to connect to any networks.

1. 3G/GSM modem connection fails with error 720 "A connection to the remote computer could not be established. You might need to change the network settings for this connection"
2. Wimax connection (Yota) goes well until "Getting an IP address...", then fails
3. Wi-fi connection to another computer looks ok, but if I open status page and look into 'details' section - it is empty, and no IP information appears. Ping another computer doesn't work

I've reverted updates, tried system restore to the beginning of the week - didn't help

I assume there are some problems with receiving an IP address, so I've checked that 'DHCP client' and 'TCP/IP NetBIOS Helper' services are started.

I've also checked device manager -> hidden devices -> 'TCP/IP Protocol Driver' and 'TCP/IP Registry Compatibility' are enabled and "are working properly"

Then I've run virus check:

• AVG Free full scan showed nothing
• Dr.Web CureIt Express Scan found nothing
• Dr.Wed CureIt Complete Scan is still running. Nothing found yet

So, now I'm out of ideas on diagnosing this problem and asking for your help here.

Answer 1

Try this if your problem is not fixed yet:

netsh winsock reset
netsh int ip reset c:\resetlog.txt

Answer 2

Please use Windows 7 Network Troubleshooting tool? It will show you a summary about your current network conditions.

And if do ping 127.0.0.1 fail, so you need to reinstall TCP/IP stack (it helps fix 3G connection problem)

If your wireless card could not get ip, or even manually setup an IP address, you still could not ping that IP address, the wireless card may have a hardware problem. (this also applied with WiMax).