Startup lock

[Bigandy769]

My son accidently hit the lock computer button.
So as a result the computer when started up displays a red screen.

Agent locked. agent 4.4.2 requires a password for system reactivation.

I can start the cpu in safe mode under the admin seting but I do not know how to unlock this agent system lock. We recieved this computer second hand and can't get in touch with the orignal owner.

Any help would be appreciated.