I've done a very stupid thing. I have a 750GB portable hard drive which was formatted for Mac. I needed to get some files off my old work PC so I took it into work and created a Fat32 partition, which my mac would recognise. Apparently this was not a good idea as my mac now only recognises that partition - all of 300+GB of music projects, software, videos, music etc is all gone. What the fuck can I do?!!