Blank screen

Hello,
Some time ago i broke the screen on my laptop and instead of boying a new one purchased a separate monitor and used that. in addition i purchased a cable to hook up tp my tv. Everything was fine until one day the volume on the monitor wasn't working. I started playing around with stuff in the control panel and ended up getting the sound back but losing the projection to the tv.
when trying to get my monitor to display on my tv i hit"extend" under control panel - adjust screen resolution-connect to a projector-extend, and the monitor went blank. I was unable to get it back to normal and then disconnected everything but nothing happend when i reattached everything . I started pressing random buttons and now i don't even hear the windows startup on the broken laptop. Can you help me, please?