Not Turning On Laptop

Hello,

Uhh, I have a problem. My laptop just had been fixed. I followed the warnings which Mom told me about it. Then later that day, I used my laptop to charge other devices(phone, tablet, etc.). Then Mom suddenly came and told me not to that so I pressed the power button to lock it first. When I pressed it again to unlock it, it says it have been misshut down or something. I pressed Enter button to continue start up but when it turned on, I can move the mouse. I shut it off by pressing the power button for long. When I turned it back on, the screen goes black with the blinking underscore on top left corner and Press Esc button for... you know what's that on down left corner. After that, nothing. Just a black screen. And it won't start Windows 7. Please help me, what do I do? I need the laptop for certain tasks. Please.