Recover deleted data from deleted partition

Recover deleted data from deleted partition

I've tried to create a new partition using windows xp with NTFS file
system, but unfortunately i lost the entire partitions i have (around 3)
and the whole 2 tb of space has been showing as unpartitioned..
I've used an application called Runtime GetDataBack for NTFS to try
recovering the files, but it did not show any files, later i tried using
Runtime GetDataBack for FAT and it did recognize files (Of course I did
not do a complete scan as it is showing 20hrs to complete). I did not find
a reason behind this as I am using the file system NTFS before the drive
partitions getting deleted and Here goes my question...
Why would it show in FAT?
After unpartitioning will the file system change to default FAT16?