I fear the data may be lost.
First try a utility like Recuva from Piriform:
http://www.piriform.com/recuva
If that fails then try gparted (http://gparted.org/) it has an option to 'Attempt data rescue from lost partitions' or another program for data recovery.
You may also try to reverse ntfs to FAT32 with AOMEI.
Next time: don't do anything to a hard drive or drive partition with data on it, if you don't have a back-up and certainly not if it is your backup.
Read the manual and be careful even if it says you can repartion 'without data loss'.
http://aomei-ntfs-to-fat32-converter-free.en.softonic.com/ clearly states: Cons - Free version limited to 8GB per partition