FORMATTING NTFS BACK TO FAT

I HAVE A 40G HDD THAT IS FORMATED NTFS THE PRIMARY DOS PARTITION IS ONLY 8Mb I CANNOT DO ANYTHING WITH THE DRIVE FOR SYSTEM NOT BEING ABLE TO RECOGNIZE THE NTFS PARTITION. WOULD APPRECIATE INPUT ON THIS MATTER. HOW DO I GET RID OF THE NTFS WITHOUT LOOSING HARD DRIVE SPACE.
THANK YOU
ROBERT E. FLYNN