No pilot light on gas oven?
According to online documentation, this model uses a glow bar.  For an oven (not a stove top) one should NOT have to press any button to get anything to ignite - the thermostat and circuitry will take care of that for you, provided everything is intact and working.  

If it were my oven, I'd open the door, remove the lower metal cover from within the oven (removing the grates first if necessary) and watch what happens when you turn the oven on.  With glow bar designs, for safety reasons, the gas valve may not even open if the glow bar has failed (when it generally becomes an open circuit).

In my experience, glow bars are not very reliable and yours may have failed "open".