Stand plant pot in a bowl or basin and fill the outer container with water. Leave for 15 minutes for the plant to soak up what it wants and then remove and place somewhere out of direct light to see if plant revives.
Keep well watered though, they can get very thirsty.
If keeping in a pot then water by the method I mentioned before - always best for any type of pot plant as the roots do all the work and the plant finds its own level IYSWIM. Always remove from the water after no more than 15 minutes or they will get waterlogged though.
If planting out then be aware that they are big self seeders and will spread if you don't keep a check on them.