Claiming unallocated disk space on disk0 on Yosemite

It all started with trying to use bootcamp assistant to install windows 7. It created the partition and started the windows installation DVD which then didn't recognize the created partition. I came back to yosemite disk utility to find that a partition has been created and formatted FAT32. I removed the 50 GB partition and since then I haven't been able to claim the 50 GB back to original partition or been able to format them again.