My computer screen is black

Hello, i changed settings on my computer and i click apply and the screen turnes black. i take the battery out and restart it. i say start it normally and it does. when it gets the the part where u have to put ur password in it goes black. but when i take the battery out and say go on safe mode i can see everything again. i eed help please. my computer type is windows 7 notebook labtop. and i just got it in sept.