I put Scott turf builder in my backyard and Scott weed and feed in my front yard. Most of my grass is yellow now. I am trying to put lots of water in last 3-4 days but still no improvement. I don't know what kind of grass I have. I live in Northern California.
Excess fertilizer will build up nitrogen and salts in the lawn and will burn the grass. This is the yellowing or brown appearance your lawn has.
Set up sprinklers in the effected areas and let the lawn become saturated to the point of run off.
Use the sprinklers every day for 7 days, applying 1 inch of water each day.
Water in the morning so the grass has time to dry out over the day.
After the lawn has dried for 3 to 4 days after the last watering, rake up the dead grass material.
You can then go into lawn repair for any bare areas.