Ok I am a little confused here. The phone was stolen? In this case I am assuming that you don't have the phone back then?
If that is the case, unless you had backed them up to a computer, cloud account or google, they are gone.
If you are asking how to get them back on the device, that you had stolen, but got back, then that is another story. There is no guarantee you could get the back in this case, but you can try the following.
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...