The Universal Serial Bus (USB) interface has been standard on Apple's Macintosh computers since the late 1980s. Users connect iPhones, iPods, flash drives and many other portable devices to a Mac through a USB port. Computer hardware can become temperamental, or even faulty, and USB ports are no exception. Users having difficulty accessing a device that connects to the USB port of a MacBook laptop can reset the USB ports. This process often makes the USB ports operational again.
Reboot the MacBook. The simplest solution to most hardware problems on a Macintosh computer is a reboot, which resets some hardware conditions.
Turn off the computer, then press and hold the "Command," "Option," "P" and "R" keys on the keyboard, and power on the computer.
Listen for the second set of Mac start-up chimes, then release the keys. It will come a few seconds after the first set of chimes. This procedure will reset the Parameter Random Access Memory (PRAM).
Power off the MacBook, then disconnect all power cords and the battery.
Press and hold the power button for five seconds. This procedure will reset the System Management Controller (SMC).
If you power-cycle the Mac and reset the PRAM and SMC, and those do not fix the USB issues, call AppleCare or make an appointment at an Apple store's Genius Bar. Each service offers a free consultation and can help further troubleshoot the situation.