Yes, you can probably get information back. As you might know, when any type of file is "deleted" from a file system, it is not actually destroyed right away. Instead the file system will hide the file from view and mark it to be written over as soon as new data arrives. So, it is very important that you stop taking data right away! Every time you write to the external hard drive, you risk writing over the information that you wish to recovery.
Yes, it's true there are a TON of different programs that can recover your photos nowadays. I can really only recommend one--Mac external hard drive recovery. They are a legitimate data recovery application and if worst comes to worst, you can actually send your card to their recovery centers if the software doesn't work.