Problem Conversion FAT32 to NTfs

Hello everyone,
I Have an external Western DIgital My book 160GB. I have 89 gb stored Inside. Yesterday Using my Paragon Hard Disk Manger 2008 Professional I used the file system conversion feature to sitch from Fat 32 to NTFS,a long process of 7 or 8 hours. Today I notice that the drive letter was Missing and I have no access to data cause they are not listed in the disk's folders. But the space is still occupied. I believe it is a software malfunction since in the hardare section nothing went wrong.
Since i have quite Importnt data stored in that disk, could someone please help my on how to recover? It would be better through paragon software I suppose...

 

Have you checked in Disk Management? Perhaps a drive letter just needs to be assigned back to the partition.