Car shuts off during a drive

I have a 2002 buick regal 3.8 motor and a couple of days ago it would turn off in the middle of driving, and i just thought it was my TPS sensor but, now i turn the car on and it goes about 15 ft and then the car turns off again and when i turn it back on it just turns on and turns off by itself and i hear a loud clicking coming from the fuse box... what can the problem be? how can i fix it ? and how much is it?

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