you can convert your drive file system from FAT32 to NTFS without formatting or losing data. Just follow the below steps
Insert your external drive into your pc and note the drive letter.
Now open run and type or paste the following command on it and hit enter
'''''Convert I: /FS:NTFS'''''
Where '''I''' is the letter of the drive to be converted.
check [http://www.tricksforums.com/2014/05/how-to-convert-fat32-to-ntfs-without.html|How to Convert FAT32 to NTFS without Formatting?]