You can purchase a hard drive SATA power supply and data cable from amazon for around twenty dollars total. From there you plug in the two HDD to your PC ( be sure that you r priary, working HDD is connected in a sata slot below the second EX: HDD 1 should be in Sata 2 if HDD 2 is in SATA 3) now click, computer management in the search bar, then click the DISK management tab, If you see [disk 0, disk1] all there that means both are connected. Now click START and click My computer, then find the new hard drive in that list of devices, now right click, or ctrl + A, and right click, copy, and paste all those files to your primary HDD.
Hope i Helped.