Start with the easiest fix - unplug your router and your ISP’s cable or DSL modem from the AC power supply, give it 30 seconds, and reconnect the AC. If this worked then it was a dropped setting in either of those devices.
A quick visual inspection of the small "Activity" and "Link" lights on the back of your computer or on the router itself will tell you if your computer is sending anything to your router. If the lights are not blinking, try another port on your router and a different Ethernet cable. If you’re using Wi-Fi to connect, see if the Wi-Fi light on the router is on and blinking.
You may have a hardware problem with the Network Interface Controller (NIC) or the software driver for that device. On your Window’s system go to the Control Panel / Device Manager and look for the "+" next to the Network Controllers group; click on it to expand that group to display the network controllers you have. If there’s a yellow "!" next to a device it means that you need to install the driver from the driver CD or download it from the internet; a red "X" means that the system has detected a hardware problem and the actually device needs to be repaired or replaced.
Occasionally everything will look OK, but the device is still not working. You can "Uninstall" the device from the device manager and then "Scan for Hardware Changes" which will reinstall the driver software. Often this corrects the problem.
Often your computer is sending and receiving information to and from the Internet, but your web browser (IE, Firefox, Safari, Opera, etc.) is the problem. A quick way to test the "end-to-end" connectivity is to open a command prompt window ("CMD" in XP’s RUN box or Windows 7’s Start Button/Search Programs or Files box) and use the "PING" command to test access to a well known site. For example,
This shows that your PC is sending and receiving data to/from the internet. If you cannot reach this same website with your browser, then it may be a browser settings issue or a virus.
- Reset your browser settings, usually found in Options, Tools, or Preferences. Use your browser’s Help function (or an Internet search - if you have a second system that does connect) to find the specific details on how to reset your browser’s settings.
- Try an alternate browser to rule out site-specific problems. You may need to download an alternate browser’s installation kit from a different computer. If another computer is not available to you, you can try running your Windows in what is called "Safe Mode". To start in Safe Mode: while the PC is booting up, tap the "F8" key; a list of options will appear, and you should select "Safe Mode with Networking".
- Still having problems? Try removing and reinstalling your current browser from Windows’ Control Panel, Add/Remove Programs and Features, for Firefox, Chrome, etc. or select Windows Features for Internet Explorer
- Check the Internet Connection Settings: Unless you know you use a proxy server, this should normally be unchecked, or set to "automatically detect settings" (Control Panel, Internet Options, Connections tab, LAN settings) Note: Some viruses or malware will change these settings!
Make sure that your antivirus/anti-malware software is up to date with the most recent definitions and run a full scan of your system. Even if a virus scan does not find anything, running a search for malicious software with s program such as MalwareBytes, SpySweeper, or SuperAntiSpyware may turn up the source or your problem. These anti-malware programs look for programs that are missed by AntiVirus applications because the software was "approved" for installation by the user, even if you were not aware of it happening.
If these tips didn´t work for you, the problem is more involved and may require hardware diagnostics or a full format/reload of your operating system, both of which can be performed by Micro Center's Service Department.