Cant Go On My Laptop (Laptop/Technical Troubles)?

I turn on my laptop and it shows the WINDOWS thing but after that the screen turns black and the only thing showing that the laptop is still on is the white blinking underscore at the top left of the screen. If it helps any, it said I had a virus around 5-10 minutes earlier. I'm not quite sure if my virus protection cleaned it up. What can I do to fix it? Thank you