Unless you did a destructive format which writes zeros over all the data previously on each section of the drive, the data may still be there. Formatting usually just zeros out the pointers to where the data is on the drive.
Maybe new drives work differently, but a few years ago I recovered a lot of photos for a friend who accidentally formatted a drive. Some photos had already been written over, but IIRC, we recovered well over half the photos.
This video gives you the basics, and also tries to sell you software that you will need to recover files.