OK! In your case, as I know, you need a partition data recovery program to help you. You should always act carefully to get back your wanted data and partition like this:
1. Stop saving anything new on this external hard drive in case that new file would rewrite your deleted data and make it gone forever.
2. Download a partition data recovery program to help you out. In fact, there are many partition data recovery programs out there. But, not all of them can work as efficiently as you think. Therefore, you should make your decision based on much researching over the internet.
Of course, if you don't want to do such troublesome stuffs, you can directly try some partition data recovery freeware online, such as Recuva, TestDisk and iCare Data Recovery Free, etc...
3. Save and back up restored data on another drive in case of data loss.
4. After the data recovery process, you can recreate a partition to replace the original one. Generally, the deleted partition often can be found in Disk Management. You can directly right click it to recreate a new partition.
Note: Next time, you should never be so careless and always back up everything important before any deletion or formatting.
Hello! I am sorry to interrupt you:
Several days ago, as my friend was formatting my PC, he accidentally deleted a partition of my external hard drive that was plunged on this PC at the moment. All the partition data was gone. It was totally an accident!
But, the partition data is really important for me. Is there a ways for me to get it back? Please answer me as soon as possible. Thanks a lot!

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