Lenovo g470 and stop at black screen

Dear Bros

I have a problem with my windows 7 on my lenovo g470. First window is ok, I run MSE and it found virus and I tried to clean all virus. But MSE take so long time so I force stopped MSE. Then restart my computer but after over BIOS and boot device menu its stopped showing black screen. I dont want to install windows 7 at all because my data were inside. please help me as you can. Thanks you.