Processors, or CPUs as we call them very, very, very seldom "stop working". You usually can only kill a processor by extended extreme overclocking, over volting, strong electrical surge (which will usually only ruin the power supply) or by physically damaging the pins or the CPU its self during installation. They just simply don't go bad.
It is almost always another part of the system that has malfunctioned.
How have you arrived at the conclusion your processor is not working?