Welcome to Nikonians! Sorry to hear of your problem.
What AF mode are you using: AF-A, AF-S, or AF-C? In AF-S mode the shutter will not release unless the cameras AF system has locked focus.
If you are using flash, is the flash ready light (lightning bolt symbol) in the viewfinder lit before you release the shutter?
If yes, is Red-Eye Reduction mode On? If yes, (assuming you are in P,S,A, or M exposure modes) Turn it OFF: while pressing the flash button and rotate the Command Dial until only the lightning bolt symbol is displayed in the top LCD display.