You can either use the phones file management system and move the files usually one at a time back to the device. Or, you can connect the phone to a computer, via USB cord and move all the file from the card to an empty folder on the computer. Then, while still connected via USB, you can then put the files on the phones internal storage. I would also suggest leaving a back up on the computer.
The only other way I can think of would be to email the files to yourself (should you not have the ability to use either of the above options). However that could take a while since email usually limits the number of files and file size.