If your files were stored on the microSD then you can attach the microSD card to the computer or simply connect the phone to the computer and enable USB mode. Your card will then be available in your My Computer. After this point you can use a recovery application like Recuva. The application features a wizard and a search filter for pictures only. Once you start the application, check it to search for pictures and mark the Deep scan option. It may take a while, but results will greatly improve. Good files will be marked with a green marker in front of the file.