Can I add butter to yeast dough which has already risen? I used yeast,water,milk,egg,sugar and flour in my dough. I forgot to put the butter the recipe called for. My dough has risen already. 

Can I add the butter after it has risen or can I make something out of what I got already?
No, you shouldn't be adding butter at this stage, it will take too much kneading and undo the rising. 

Whatever it is you were baking, just go ahead and bake it this way. There are many breads which don't use any fat at all. The taste will be different than with butter, but it will still be a good bread.