I changed my external hard disk to ntfs from fat32 and it did well but i can't open the files in the briefcase a mesage comes (the briefcase cannot be opened because the disk is inaccessible)
Was the briefcase located on the external? To change from fat32 to NTSF you need to reformat, which would have erased all data from the external. Set up a new briefcase and see if you have the same issue.