Monitor problem or CPU?

[smarch]

Had a user working on an older pc and monitor when it the monitor suddenly went black. CPU seems to be find, fans and lights are on.
She thinks she accidently typed a series of keys that locked it or made it blank. Wasnt sure if this was possible.
We have tried replacing the card in that pc with the same results, then hooked up the pc to another monitor with a new cable and get the same results. Seems to be the pc then.

Any ideas on how we can unlock this?
Thanks!
Sandy

 

[Lemon13]

She thinks she accidently typed a series of keys that locked it or made it blank. Wasnt sure if this was possible." - all blank afik not possible, there will be at least a blinking cursor in the upper left corner.

there is no boot up screen/logo coming and the monitor light is on (green)?
take out grafikboard and turn on pc. do you get some beeps? if yes cpu is ok, what means either grafikboard or motherboard is dead.