I have used partition recovery software to recover hard drive partition, by using this you can get all your lost or erased data from your external hard drive. You can download the free demo version of this software to recover lost data. If you satisfy with evaluated result you can use full version of this software to save recovered data.
just erased partition on my external hard drive,how can i get them back..?
No need to panic, I had also faced a similar problem with one of my external hard drive. Using the external hard disk recovery mac software, I had recovered all the data that was present on my hard drive. This utility restore data from hard disk drive having HFS+, HFSX formatted partitions or volumes.
Just download the trial version of this software and if you are satisfied with the recovered results, you can purchase the full version.