the car was running fine. i came home from work, shut it off, and 15 mins later it started and ran really rough for a few seconds and i havent been able to start it since. error codes 406 and 257 came up with a scantool. help me please

p0406 and p0257? the first one is for a faulty/dirt EGR valve and the second one is Injection Pump Fuel Metering Control. the first one can cause a rough idle but shouldnt make the car imposible to start. p0257 is a little more serious and im not quite sure what triggers that code. is the fuel pump working (if you turn the key to the ON position, can you hear the pump buzzing?) when you try to crank it does it try to start but doent quite catch, or does it start up and then die out? also will the car start up if you open the throttle some? (with the gas peddle) give us as much detail with symptoms as possible. thanx
maybe someone with more DTC knowledge can tell you what P0257 means.
Matthew

the car does not start but it sounds like it wants to. i dont think i hear the fuel pump kicking on either. thanks for the info