ubtuntu 14.04 usb port not working

不知是更新还是删除一些旧包导致，所有USB接口都没法使用了。网上找到

For Grub2 Users (Ubuntu Karmic) follow this procedure

gksudo gedit /etc/default/grub

Find the line

GRUB_CMDLINE_LINUX=”"

and place the boot uptions there, like

GRUB_CMDLINE_LINUX=”acpi=force irqpoll”

Save and exit the file

After that, update the bootloader with:

sudo update-grub

最后，重启

sudo reboot

ref：http://www.ubuntugeek.com/how-to-fix-usb-stops-working-problem-in-ubuntu.html