Spray it with water and bake it in the oven on a low temp for a few minutes. Not sure how long, but just keep checking it.

I've done a similar thing to romanigrl. I was taught to spray a brown paper bag with water, put bread inside, place in low temp oven for a few minutes. Just keep an eye on it as you don't want the bread to burn or get too hard. The water creates steam and it'll soften. I think there is a variation where you put it in the microwave as well, but I haven't had luck with that as the bread just seems to get very hard once it cools off.

You, can sprinkle the bread with a little bit of water, but be sure to seal it in foil, tightly. Then bake it on the over for at 325, for 10 minutes. Make sure the ovens hot, otherwise it will not work

Thanks!