There are some data recovery programs that could do the job. You could search for them over the Internet.
If they don't help you, then you could try to access the data using Linux Live USB / CD. Within the Ubuntu forum you can see the steps how to make a bootable flash. Once you have downloaded the .iso file, change the boot priority on the computer where the SD card is placed. It is done through the BIOS and you must change the boot priority to be from USB ports and not the HDD. When it boots from the PC, you have to click on try option and not on the option to install the OS.
If Linux can't help you please, follow these steps:
1. Open command prompt
2. Type the following:
attrib -h -r -s /s /d X:\*.* Then hit "Enter" and wait about for some seconds
Be careful! Respect the spaces between words and script. Change the letter X with that has been assigned to the SD on your PC (that you can see it in My Computer. It can be anything, depends on each computer.)
3. Finally, browse the flash drive and delete the recycle folder and if there is another one called "Autorun" you have to delete that too.