How to Clean USB Ports
Most problems with USB devices occur because of a broken device or a software problem. You can usually fix USB device problems by rebooting, reconnecting the device or updating either the drivers or Windows. If no USB devices work in a particular port, the port may have a bad connection caused by dirt and dust. For safety, turn off your computer and unplug it before cleaning the ports.
Cleaning With Air
If your USB port is filled with dust but doesn't have anything else stuck in it, clean it using a can of compressed air. Before starting, pull out any large dust balls with your fingers or tweezers. When spraying air, keep the can upright to prevent it from leaking liquid. Most USB ports do not open into your computer case, so you don't need to worry about blowing dust onto other components. Spraying air into a port can potentially compress dust further inside the port, however, so aim the nozzle at an angle to avoid making the problem worse.
Cleaning With Alcohol
Wet a cotton swab with isopropyl alcohol and insert it into a USB port to clean out stubborn dust and sticky messes. Wipe all around the inside of the port, including on the contacts. Any common concentration of isopropyl alcohol, such as 70 percent, 91 percent or 99 percent, will work safely, but lower concentrations take longer to dry. Don't turn your computer on until the port has dried out completely to prevent damage. The alcohol will evaporate on its own within a few hours. Speed up the process by absorbing some of the moisture with the corner of a lint-free cloth. Don't use another cotton swab to dry the port; you might leave cotton debris behind.