Sony PCG-GRT230 VAIO User Manual page 177

Why did the computer screen (LCD) go blank?

Your computer screen may go blank if the computer has lost power or has entered a power saving mode (Standby
or Hibernate). If the computer is in LCD (Video) Standby mode, press any key to activate the computer screen. See
Using power saving modes

Make sure the computer is plugged into a power source and is on. The power indicator on the computer will be on if
the computer is on.

If your computer is using battery power, make sure the battery is inserted properly and is charged. See
Battery for more information.
 If the display mode is set to external display, use the Fn+F7 key combination. See
information.
for more information.
Using the
Selecting a display for more
Page 177