2000 mercury sable everything stopped working at once

Start checking from the battery terminals with a voltage tester or light, work your way to the main fuse panel where the positive cable goes into it then work your way down to the alternator and starter. It sounds like you have lost power someplace. It could be a starting/charging fuse/circuit breaker in the main fuse box. They look like giant fuses. There are also 2 fuse boxes in most cars these days, one in the engine compartment and one or even 2 inside the car, either under the dash and on one end of it or one on each side of the dash where you open the doors.

Which tire was it that blew out? The reason I ask is, the wiring harness to most electronics are close to the fender well in front driver side. I've seen first hand the damage a flat tire will do to harness there it shreds the wires.

Why my 2000 mecury stable suddenly stop, after my merchant's installed a new an alternator? Tell me why? Moreover, he had seal my pipe.