Just make use of Remo Recover Mac tool, with this you can restore that partition along with all the files as they were before. In such instance, do not panic suddenly as your data not lost forever instead hidden in hard disk only. However, sometimes if may lose partition data when you do not follow proper procedure or else while choosing to modify option if you go with delete option then whole data stored on that partition will get deleted.
Most users always wish to resize their existing partition for making a number of partitions for managing stored data. With this tool, you can enlarge or shrink the size of an existing partition regardless of whether the drives are internal or an external one. Mac OS X comprises of Disk utility application that helps you to resize disk partition and even you can modify a mounted volume.