If it's the Carbonite map you have several options: If you can still see the map right click on the map frame and choose "Reset layout" in the menu. Type "/carb resetwin" (without the quotes) in chat. Open Carbonites options (type "/carb options" in chat, right click the Carbonite minimap button and choose "Options" in the menu, right click a non-icon area of any Carbonite map and choose "Options" in the menu) to the "Reset" page, and choose "Reset window layouts of current character". Clicking this option will automatically open a "Reset window layouts" confirmation box. Choose the "Reset" button, and you should be good to go.
If it's the Blizzard map, I have no idea what you might do.