Under Disk Management in the computer look there to see if its mounted but shows up as not formatted or not partitioned. It might be there but no drive letter assigned. If you see it there DO NOT PARTITION OR FORMAT IT... instead you will need to run software to scan this drive and correct for damaged file tables.
If the drive is not detected there then the drive may be damaged. If under warranty you could return the drive for a replacement but all data would be gone and potentially in the hands of whoever gets your dead drive. Or you can open the enclosure and mount the drive as a slave drive into a desktop computer and maybe then see it in disk management to work on its data recovery or if its the USB to SATA daughter board that blew on the external enclosure through this process of power loss, then your drive might mount up and get a drive letter as a 2nd hard drive in the computer in which all data would be accessible without a data recovery process needed.
