If you deleted them a while ago, then there is almost certainly no way to get them back. The longer it is has been, the more likely it is that other data has overwritten the location on the phone where they were. Now if it was really recent, you might get lucky. Might.
While there is no guaranty that you can get them back. Deleted does mean deleted. There are a few apps/programs out there that 'may' be able to help you recover the data.
A few of the programs you could try would be... DiskDigger, MobiSaver, Android-Recovery and Tenorshare. They are all data recovery apps/programs. There are many others out there, so check around and see which you would rather try. There is also one called RECUVA, that I have heard is free, which you...