Toshiba Satellite C55-A - Manual (Page 113)

Sound system
In addition to the information in this section, please also refer to the
documentation supplied with your audio device.
Problem Procedure
No sound is heard Press the function keys to increase or decrease
volume.
Check the software volume settings.
Please check to see if Mute is turned to Off
Check to make sure the headphone connection is
secure.
Check within the Windows Device Manager
application to ensure the sound device is enabled
and that the device is properly working.
Annoying sound is
heard In this instance you may be experiencing feedback
from either the internal microphone or an external
microphone connected to the computer - please
refer to
Sound System and Video mode for further
information.
Volume cannot be adjusted during Windows start
up or shut down.
If you are still unable to resolve the problem,
contact TOSHIBA Support.
External monitor
Please also refer to Operating Basics , and to the documentation supplied
with your monitor for further information.
Problem Procedure
Monitor does not
turn on After confirming that the monitor's power switch is
on, you should check the connections to make
sure that the power cord/adaptor is firmly
connected to the monitor and to a working power
outlet.
User's Manual 6-12