recovering the soil in a yard where vegetation killer was used.

Hello everyone.

We have a big backyard where Scott's Vegetation Killer concentrate was used this year and in previous years. The company told me the soil will not allow anything to grow for at least a year - maybe two years. We now have the opportunity to turn this yard into a beautiful paradise! What should we do to support bring the soil back so we can plant grass and plants? We are also having a tree cut down and another one trimmed. Wood and leaf mulch can be very attractive and could temporarily "stand in" for grass. Would it be harmful to the recovery of the soil to presently spread some of the tree mulch in the yard? I've read that mulch will not prevent me from fertilizing the soil. Will it hurt the soil? Will it make the vegetation killer last for a longer period? What kind of fertilizer should I use and when should I use it? I am completely in the dark about how to bring this soil back to good health. Any help you could give me would be useful.