If the ULS log files remain empty (0 KB) take the following steps to resolve:
  • Make sure you have enough space in your hardware driver.
  • Check timer and tracing service accounts information, the tracing service must use the account as Local Service.
  • Reset the timer service account password.
  • Restart the tracing service.
  • Check Diagnostic logging under Central Administration site, you can refer to: http://technet.microsoft.com/en-us/library/ee748656.aspx
  • Check the permissions on /14/logs folder

See Also

Source

http://social.technet.microsoft.com/Forums/en-US/sharepoint2010general/thread/e327f833-5e43-42d1-a330-f2d16c41106a