Sony Vaio Will Not Get Past the Blinking Upper Left Hand Cursor Page?

My Vaio, PCG-7D2L, when booted up flashes normally the Sony Vaio Logo and then proceeds to a blank black screen with a blinking cursor in the upper left hand corner. I have tried a bunch of internet remedies with little success. It has booted up successfully 2 time in the past eight months. I could not even tell you how I did it. It was probably just luck. It did tell me though, that the computer itself must still be ok. Right??? Thank you in advance for your information.