Continue to get 500 internal server error

I was installing the plug in’s and moving on to the demos and i keep getting “Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, 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.”

I’m frustrated… please help 🙁