Rdkid

Hey guys I got a Seagate external hd, was working well, it came with drivers in the drive folder, one for windows and one for Mac, after sometime I accidentally double click the Mac driver icon and now the system only recognizes 1tb of the 4tb. I used there desktop software and it recognized the full capacity, disk manager has unallocated space for it but I can't allocate it . help me plzzzzzz