My 2005 Marquis won't start after sitting for a week,any solutions?

Use a gage and check fuel pressure, engine cranking. The initial prime is good as far as it goes, also, hearing the pump run doesn't mean it is making good fuel pressure. Did you visually check for spark at the spark plugs? If your missing rpm signal it can cause several issues. Don't replace anything unless testing points you in that direction.

start simple, is that battery good, is there something draining your battery like a stereo of interior light or door or trunk not closing. if it isn't battery or starter related and you get it started but runs rough, does it smooth out after the engine has ran a while?

No the battery has plenty of juice.And it never ran rough. No it will not start with ether. I am changing the plugs tomorrow and go from there. Thanks for the ideas.