How to fix a broken LCD on an SLR?

Last night my Nikon D3000 was in the car, and when I woke up this morning I found the LCD screen displaying a crack running from the right side to the left. The camera turned on fine but half of the screen is now black with thin white lines running. I don't know what that means. The other half shows the menu and the photographs. I took some photographs but the camera has stopped focusing. Don't know what to do!

Check out the Nikon website assuming you do not have a warranty. You can send it in. Relatively expensive but check it out. If it is new with the receipt to the place of purchase.

Sorry but the factory warranty is for their mistakes not yours. Check with a pro about a replacement.
It's going to cost you but perhaps now you'll remember to bring it in and put it in its bag.