Why do I have a blank, black screen?

I haven't used my dell for about 1.5 years I was using a different computer. I think my dell was hacked, because it was locked and it said I needed to put a money code within 48 hours. I never did that and after that I just let it sit and know all I have is a normal startup, I enter my password. After that I should have my background and internet and toolbars, but all I have is a black screen with my mouse, I can move my mouse, and do control alt delete, but I have no options, I'm sure this is rare, but If you have any little bit of info, please let me know!