2nd monitor isn't showing any signal

[Sklgy_RecKLesS]

so i have 2 monitors working perfectly fine
but today i restarted and my 2nd monitor stopped displaying anything
its still working once i open folders/winrar it opens on the 2nd monitor but the screen is black
and i can grab from the 2nd monitor to the main monitor what might the problem be ?

 

[Phillip Corcoran]

Confirm that the problem monitor actually works by either using on it's own or testing it on another PC, because I suspect the monitor itself may have packed up.