Dell laptop hooked to external monitor-no picture

[devilynn]

The screen on my husband's Dell computer broke so he hooked it to an external monitor. It has been working fine until a few minutes ago when our pet rat walked across his keyboard. You can see his mouse on the screen of the external monitor but the rest of the screen is black. Any idea what key(s) the rat might have stepped on to cause this?

 

[DeathRabit]

Reboot laptop if this no solve this, try use special keys on keyboard some are responsible for display options.

 

[devilynn]

Thank you for your response. He got it working again but is not sure how he did it.