When I lose an engine I usually immediately flip the apu start button. I then put the problem engine to the idle position. Many times it just starts up. If not the APU is already running to try a normal start..
Note: if you are going to shut down the running engine as noted earlier, make sure the APU is running and the APU generator is switched on.
Also make sure the fire handle isn't pulled on either engine. Most of my engine failures have been caused by a mouse click while flipping through the waypoints on the upper entry panel.