I know absolutely nothing.

So, my son decided to try and upgrade his store-bought PC with a different processor and more RAM.

Long story short, it didn't work so he simply put the original pieces back in and now the monitor is saying there's no computer found.

Is there a simple solution, like a reset button, for when you pop-out and reinstall the CPU or something?

Did he mess with the BIOS? Try resetting it to default settings.

Are you getting the beep when the computer powers on?

If it has them, can you hear the hard drives spinning up and reading/writing?

Did he re-seat the memory properly?

Unfortunately, it's very likely, if he's not experienced, that he fouled up the chip socket.  There are tons of tiny little pins under there that are easy to damage/bend.

Could be something as simple as he didn't ground himself before diving in, and a static shock messed something up.

All good points.

Thanks for the reply.

He's 15 and just dove in.  I guess it's off to the repair $hop.

Anyway, thanks for the responses.

I would reseat the memory first.
Maybe even try one ram stick at a time.

Take a nice close up pic of the socket. If you get the light just right we'll be able to see if there's any bent pins in the socket.