Does the issue appear all the time or is it an intermittent issue? May we have the exact model name and the current operating system of your Sony Vaio computer? Let's try to isolate this, please follow my suggestions below:
Power cycle the laptop. Shut it down, remove all connected devices especially the AC power adapter. Uninstall the battery then hold the power button for 5 seconds. This will drain the remaining electricity from the unit. Install the battery, plug in the adapter and test it again.
Test the screen while in BIOS. You may reset it as well.