2007 Pontiac Grand Prix not starting

I got this grand Prix that's a 07 and it was
running fine the last few times I drove it but
it's been sitting for a year now and won't
start. It acts like it's not getting any gas but
there's a half of a tank I put in there when I
got the vehicle, around a month ago. I can
hear the pump turn on and I changed my
relays and the problem still continues. The
check engine light came on and I had
someone get the code from it and it says it's
a fuel pressure problem, is it my pump or my
filter?