What might be wrong with my 1995 blazer? the blinkers and brake lights went out at the same time.

Well to be honest the question and subject title is a bit vague. BUT! if your lights went out after installing the sub i would say check all your wiring from stereo to amp to speakers. If that isnt invloved and your lights have gone out start by checking your owners manual and looking up the fuse diagram for your vehicle. Check those fuses. The Fuse box in your vehicle is located to the left of the instrument cluster visible when the driver side door is open there is a cover with a latch turn the latch to open it. There may also be a possibility of it having a relay which would be located in the other fuse panel located under the hood of your behicle next to the air filter.