I have the same problem like him (USB Keyboard & Mouse Stopped Working (Ubuntu 14 LTS))
It happend after nothing (no possible reason), I mean no updates or software changes were running before a system restart.
A timepart solution seems to be changing in the grub menu the run ubuntu in old kernel version (oldest helped me only).
But this is not the first time (last time I completly reinstalled Ubuntu).
This is very annoying problem.
Who can help to make a long therm solution? (Mouse and keyboard via USB).
Thanks!
