No micro wave!
Just heat the broiler on high. Then stick the steak in until the outside gets bubbly. Turn over and do the same. It should save the inside as much as you can.
Otherwise: wrap in foil with a little water and butter (I put in some garlic and stuff I like) in a hot oven for awhile and hope for the best. But at least you will get some nice juice with it.
But both methods are not going to stay medium rare or whatever!