Sick maple

[Zkolic]

I have a 4-5 year old maple tree in the backyard with no other trees surrounding it. I've noticed a couple of days ago that the leaves were turning yellow like they would in the fall and today the leaves are completely yellow like they would be in late October, how could i save this tree ?
Any advice appreciated, Thank you

 

[JeffL]

Is it wet? Dry? Have there been any significant changes in the area surrounding the tree? How is it currently set up now? Mulch ring? Just grass right up to the trunk?