2002 Mercury Cougar Speaker Problems

Hey my name is Russ and I have a question. In the beginning my car sometimes my left front and rear speakers in the middle of a song just shut off all the sudden and won't go on until wait like 10-20 minutes and turn the car on again the speakers are fine.. Now, the speakers absolutely will not go on at all. You can hear sometimes a pop or something in the speakers. Has anyone had this problem and if so how'd you fix it?