Windows 7 No Internet access on wireless network

[Confused2011]

I have a Sony Vaio laptop, running Windows 7 Home Premium 64bit, Up until 2 days ago I had absolutely no problem using its wifi and/or staying connected to the Internet. Two days ago, however, while being on Skype, my Internet connection got disconnected unexpectedly.  With windows Network Diagnostics,I sometimes get "The DNS server isn't responding", and sometimes "Local Area Connection/Wireless Network Connection doesn't have a valid IP configuration"OR "computer is trying to use a DNS server that is incorrect or doesn't exist."

Even with the cable I am not able to connect to the internet so I can't update the network adapter or fix the problem online. Looking at the 'Basic network information and set up connections' (in Control Panel -  Network and Sharing Center) I see my laptop (sometimes connected, sometimes however the line between the laptop and the 'unidentified network' has a yellow triangle on it)  and I can see the 'internet' with a red X on the connection line between that and the 'unidentified network. 
When checking the 'Wireless Network Connection Status' it's showing  that it's connected, activity's showing 'sent and received bytes' but says 'no Internet access' to both IPv4 and IPv6 connectivity.

I read lots of blogs and advice and tried many of those 'fixes' that were recommended, some of which were the following (shorter versions): 

- unplugging and replugging the power cable to the modem
- resetting the wireless router
-rolling back driver
-  obtaining IP address and DNS server address automatically for Internet Protocol V4 and V6
-changing the "Preferred DNS server" to 208.67.222.222.  Later repeated it and changed the "Preferred DNS server" to 208.67.220.220
- netsh int ip reset (CMD)
- netsh winsock reset (CMD)
-reset TCP/IP
-disabling IPv6 
- clearing browser history
- system restore to an earlier point on my laptop
After each change I restarted the laptop. 

None of the above worked. Right now under 'status' it's showing:
IPv4 connectivity: no Internet access
PIv6 connectivity: no network access
 I've used this network for a while and this is the first time this problem has occurred.
 
Be it network driver issue or a patch of some sort i may need to download, until i can connect to the internet, I can't fix this problem on my own. In the meanwhile no other computer or phone with wifi in the house has any problem connecting to the Internet. 
I took it to a computer technician who said I need to reinstall Windows 7. But none of the many blogs here and elsewhere I read even remotely mention that. Is that the only solution? 
Before I'm messing up the system even more, I wanted to ask the Expert! What am I not doing right in fixing this issue?

Any help is greatly appreciated.

 

[Mike]

From a diagnostics perspective, I would say you have covered everything. If you have a Dell laptop or a laptop with an Intel Wireless NIC, you should be able to run a set of diagnostic tests on the wireless transmitter and receiver. These tests will help you determine if there is a hardware fault. Look for this next. Are other systems on the network experiencing the problem? If not, you may have a hardware fault, or some kind of irreparable harm to the device configuration in the registry.

How old is the laptop and have you used it extensive for wireless before?
If anything, what changed?

The only thing I can think of is that DHCP is not being sent down properly, and one way to test this theory is to see if other wireless devices on the network still function properly under automatic set up. If they do not, the problem is with the router. If they do, the problem is most likely with the laptop's WiFi card.

One quick method on most Cisco-Linksys routers is to set default gateway to 192.168.1.1, set custom DNS servers, and see if you can gain Internet access.

I have detailed some quick ways to solve network difficulties on a software level in Windows here:

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In most cases, the problem is similar to what you are reporting. However, a fault wireless NIC can very well stay in a defunct state after connecting to the router. If you perform all of these operations, you should now start looking at hardware diagnostics testing. This can be accomplished with utilities found on the Dell Support website or using the Link Removed - Invalid URL.

 

[Mike]

Even with the cable I am not able to connect to the internet so I can't update the network adapter or fix the problem online.

This is more indicative of a problem with Windows than a specific hardware problem. In theory, for it to be a hardware problem, both the WiFi card would need to be fried as well as the wired NIC/ethernet port. It could very well be severe corruption in Windows. Can you remember making any changes that would have led to these connection problems happening? Again, if other devices are able to connect without difficulty, and System Restore doesn't change anything, you may very well be in a scenario where you have no recourse but to backup and re-install. I do not see how you have performed all of these diagnostics and still can't get a connection.

 

[Confused2011]

Hi Mike,

Thank you so much for your response. My laptop is about 2-3 yrs old and I can only remember having to use the cable only once or twice. Even then, the wifi worked just fine, just chose to use the cable. Because I had no problem with wifi or cable before, I never checked what the settings should be, so I have no idea what has changed.
As I mentioned earlier, I tried to follow what worked for other people when they had the same problem and what helped them fix it. It was in one of the blogs/threads that obtaining DNS server address for IPv4 needed to be not set to 'automatic' but the number 208.67.220.220. (or 222). After putting in one of these numbers, the Wireless network connection status showed IPv4 as 'internet' or 'connected' (sorry, can't remember) but IPv6 still showed no Internet access. At that point the otherwise dotted line between my laptop and the network adapter/router became a steady, straight line (no yellow triangle or 'x') and so was the line between that and the internet. It looked like i was connected but still couldn't connect to the internet. So then I googled how to fix IPv6 and a few blogs recommended completely disabling it as (they said) it was unnecessary. I did that and then IPv4 went back to no internet connection. While I traced back my steps and undid the ipv6 changes, restarted the computer, there was still no Internet or network connection for either IPv4 or IPv6.
I'm not sure what may have changed since a few days ago, when I still had Internet as I did not download any new software or otherwise changed anything. I was wondering if possibly a windows update may have caused all this but not sure of that either. So far I can still connect to the Internet wirelessly with phones and iPad.
I will look into your suggestions and will let you know of any outcome.
Again, thank you for taking the time to respond.