Hard Drive Partition Accidentally Deleted :3

Hello, I went out and bought a new External Hard Drive and partition it, Later on i accidentally made a mistake and deleted the hard drive that i partition. I wanted to know how i am able to retrieve my disk drive that my external hard drive booted from, cause since i deleted the partition i can’t even see my external hard drive now. Now the program that i have on my computer is “Partition Table Doctor” and i was wondering if that program would do the trick? Sorry new to this… never happened to me before… deleted a partition that is… any help is welcome, thank-you sorry that you have to deal with a noobie like me