Apache Server Port 80

Question

Internal Server Error
The server encountered an internal error or
misconfiguration and was unable to complete
your request.
Please contact the server administrator,
[e-mail] and inform them of the time the error occurred,
and anything you might have done that may have
caused the error.
More information about this error may be available
in the server error log.

Apache Server at www.youtube.com Port 80********************************************************************how can I fixed the problem?