So I have an external 4TB drive. One 1,5TB Partition (HFS) and one 2,5TB partition (exfat). I have moved all my data from the exfat partition to the HFS partition, and I no longer require to have a exfat partition as my windows pc is gone. Therefore, I have deleted the exfat partition using disk utility and it has automatically resized the HFS partition to a fully 4TB. I clicked OK, then both partition has disappeared and OSX can only see the drive itself, but no partitions. The data on it was pretty important and I have never experienced any problem with HFS resizing before... What could be done? No DVD drive is in the machine, therefore linux and windows applications are out. Thanks!