After reinstalling Windows did you install the chipset drivers?  If not, these drivers are the first drivers you need to install.  Without the chipset drivers, Windows will not be able to recognize any of the hardware integrated on the motherboard, such as USB devices, network adapters, etc.

Steve

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@volcano11 wrote:

After reinstalling Windows did you install the chipset drivers?  If not, these drivers are the first drivers you need to install.  Without the chipset drivers, Windows will not be able to recognize any of the hardware integrated on the motherboard, such as USB devices, network adapters, etc.

Steve

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Click Start, and then click Control Panel. Click Performance and Maintenance, click Administrative Tools, and then double-click Computer Management.

This will open the Computer Management Terminal.  This is one of the greatest areas to visit on your PC (IMHO).  Now expand the Device Manager section.  Look for any exclamation marks beside devices.  As Steve has mentioned above, you will most likely see errors here.

You wrote ”I reformatted my inspiron a while ago but now my USB doesn't work.”

1) If you mean an external USB device you connect to the computer does not work, the device driver could lose the compatibility with Windows XP SP2 update. If that is the case, discuss with the vendor for further information.

Try the following service whether you can verify the compatibility.

Go to Start menu --- Control Panel --- Performance and Maintenance --- System ---> Hardware ---> Driver.

Alternatively, you may want to test with a known compatible USB device to connect the ports. If this works, then the cause may be the USB device issue.

2) If a specific USB port does not work, try connecting the device to another USB port. If another port works, then the first port may be damaged.


Related document (Document Number: FA1016572):

http://support.dell.com/support/topics/global.aspx/support/kb/en/document?dn=1016572&c=us&l=en&s=dhs&cs=19