Suddenly cannot connect to the internet

Ive been able to use the internet perfectly up until now, but after turning on my computer although it says it is connected to the router it says "no internet access". Ive tried all the usual things like restarted my router and wireless adapter (i have a desktop, but i use a laptop usb adapter as i dont have one built in. all other computers on the network can access the internet, its not a problem with signal as ive tried moving the router closer, and also ive tried using a wired connection from the router to the computer using an ethernet cable, but i get the same problem. After doing a bit of googling i found a suggestion for trouble shooting that suggest that i try to ping the default gateway, which i have done and it fails each time, it also cannot ping other computers on the network. i tried pinging its own ip address and that works fine. Other things i have tried are temporarily disabling the firewall, and clearing the arp cache (dont really know what that is i was just following a suggestion.) I dont know my exact router model but im with sky broadband and it a netgear my wireless adaptor is a bt voyager 1055 I literally have no clue what has gone wrong so any help would be appreciated. if i cant find something intelligent to do soon im just going to completely reset my computer and reinstall everything.

Hellow Matthew, and welcome to WTT Forums,

This may get you started, but I will shortly be away from my keyboard and will be a while before I can check back.
Hopefully other Techs will read and provide suggestions for you more promptly.

Here are a couple of starting points.

1. USB devices sometimes have faiure, not because of the device itself, but because of a corruption in the way that Windows sorts the various USB ports.
Please consider following the recommendations from Ztruker, here:
http://forums.whatthetech.com/index.php?showtopic=97497

2. It may be that the actual device driver has become corrupted, and a simple uninstall-reinstall will help.

3. But since you also state that attempts to connect to the internet by Ethernet cable also fail, then the machine may have a corruption of the Broadband device of the machine.
Consider using a known-good machine to navigate the the desktop's Manufacturer website.
Find the Broadband device driver appropriate to the machine.
Consider uninstall and reinstall of that device.

4. Check the USB broadband device by using it with another known-good machine to determine if it is capable of functioning properly on a known-good machine.

5. Have a look in Device Manager. Are there any yellow or red warnings? If so uninstall and reinstall for each.

6. Please also provide more information about the specific machine brand and model number so that we can more intelligently provide suggestions.

Best Regards

Also check your browser - Connection - LAN settings. In most cases (unless you are intentionally using proxy settings) the LAN setting should be set to: Automatically detect connection.

Click on Start then Run or press Window key (next to left Ctrl key) +R and paste the following into the Run box, exactly as shown, including double quotes:

cmd /c "ipconfig /all > postme.txt & ping yahoo.com >> postme.txt & notepad postme.txt & del postme.txt"

and press ENTER.

A file will open in Notepad. Please copy and paste the contents here. Close the Notepad window and the file will be deleted and the Command Prompt window will also close.

If you don't have a Run selection off the Start menu, see here: Enable Run Command on Windows 7 or Vista Start Menu