Well, first of all, you can STOP putting URGENT in the headlines, because doing is is indeed childish and pointless, and mostly points towards your inability to do proper planning.
I don't care the least if it's urgent for you. That's your problem. You don't pay me (or anyone else) for help - so even the double pay required for URGENT jobs is zero. Understand? Good.
Now to solve your problem (of course you should have done all these steps already as it's just basic troubleshooting):
1) Make sure your power supply can supply more than enough current (>2 times the rated current of the solenoid would be comfortable). If not, get a suitable power supply.
2) Connect your 12V power supply directly to your solenoid. Does it move? If not, it's broken. Get another solenoid.
Now you verified your solenoid actually works, and you can continue.
3) Verify your transistor can handle the current the solenoid requires to operate. If not, get another transistor.
4) Hook up your transistor - collector to solenoid, emitter to negative pole of the power supply. Through a resistor (about 1k) connect the base to the +12V of the power supply. Does this switch the solenoid? Great, your transistor is working.
Time to continue with the Arduino:
5) Connect your Arduino: pin via resistor to base; GND to negative of the Arduino.
6) Open the Blink sketch; change the pin number to match the one your resistor is connected to.
7) Double check that the pin your resistor uses is the same as you use in your code.
8 ) Run the code. Your solenoid should be clicking on and off.