What happen to my camera (Nikon D70s)?

I have Nikon D70s with 28-300mm lens and when i bought it it worked really good. Every Picture was clear and all that. But now, after few years, the pictures are not coming out so good. And it didn't happen just one day it. Please help me, what is wrong with it? Can i fix it?

Added (1). So before I could make close up pictures that had really good focus and good contrast and the light was good.
Now: The pictures are either to light or to dark, I can't make so close up pictures as i did before because they don't have good focus.

I'm in Photo 1 in my high school and I know little of the basics stuff.

Added (2). How do I restart the settings?

If you knew the basic principles of photography, you would be able to adjust the camera properly to adapt to any given scenario. You would also be able to narrow down the exact problem so you can get more helpful advice. "Clear and all that" and "not coming out so good" are so vague. You'll just have to ditch the dSLR and buy a point-and-shoot.

See if you can borrow a Nikon lens from somebody and try that. You have three possible problems: the lens isn't working right, the camera isn't working right, or the camera settings are wrong.

If you can't find a lens to borrow, take it to a camera store (preferably a dedicated camera store) and ask one of the sales people to look at it. They'll be able to help you.

I also have a d70s. Try learning about photography to be able to fix it.www.digital-photography-school.com is a great site with tips for beginners and pros alike. Or try having your sensor cleaned but other than that you didn't say what the actual problem is.