Accidentally formatted with a twist

Don't reformat!

You need to look for a tool to do an unformat. How valuable are the photos? For maximum chance of retrieving the photo consult the professionals, driversavers.com.

It's a good idea to make a copy of the drive. /Applications/Utilities/Terminal

# I know that I haven't provided enough info here, but it's just to get you started.

dd if=/dev/disk0 bs=4096m | dd of=~/disk0-s10 bs=4096m

You will need to figure out this name:disk0 and it will not be disk0

"Stellar Phoenix Macintosh - Mac data recovery software, recovers data from damaged, deleted, or corrupted volumes and even from initialized disks."

They have a trial version, so I guess you can see if your data can be recovered...

http://www.stellarinfo.com/mac-data-recovery.htm

"Data Rescue II is the best data recovery software on the market for recovering files from a problem hard drive. Data Rescue II works when other tools fail. Data Rescue II is also completely safe to use since it does not attempt any risky repairs to the drive while its scanning."

http://www.prosofteng.com/products/data_rescue.php

FileSalvage is an extremely powerful Macintosh application for exploring and recovering deleted files from a drive or volume. FileSalvage is designed to restore files that have:

-- been accidentally deleted.

-- become unreadable due to media faults.

-- been stored on a drive before it was re-initialized/formatted.

http://subrosasoft.com/OSXSoftware/index.php?main_page=product_info&products_id= 1

"TestDisk is a free data recovery utility. It was primarily designed to help recover lost data storage partitions and/or make non-booting disks bootable again when these symptoms are caused by faulty software, certain types of viruses or human error (such as accidentally erasing a partition table)."

http://en.wikipedia.org/wiki/TestDisk

Wondershare Data Recovery for Mac

"Recover lost photos, video, documents, email and archive files from any Mac-based hard drive or external hard drive, iPod, USB drive, SD card, digital camera, mobile phone, and MP3/MP4 player, due to accidental deleting, formatting, virus infection, improper operation, unexpected power failure, and other unknown reasons. Also, iPhone recovery allows you to recover lost photos, videos, SMS, contacts, note, calendar and call history from iTunes backup file. With the free trial, you can preview all your recovered images, videos, music, documents and archive files prior purchasing this Mac Data Recovery."

http://software.bigbigsoft.com/data-recovery-mac

most likely, it will be dosfat32 format as /dev/disk3 is.

mac $ diskutil list
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:          Apple_CoreStorage                         999.3 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS Macintosh HD           *999.0 GB   disk1
                                 Logical Volume on disk0s2
                                 B5476F09-70EA-41C6-8655-72485151AD19
                                 Unencrypted
/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *4.0 TB     disk2
   1:                        EFI EFI                     209.7 MB   disk2s1
   2:                  Apple_HFS 4T Virtual Machines     999.3 GB   disk2s2
   3:                  Apple_HFS 4T Backup - Time Mac... 2.9 TB     disk2s3
   4:                  Apple_HFS 4T Boot For Fun         103.7 GB   disk2s4
/dev/disk3
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *2.0 GB     disk3
   1:                 DOS_FAT_32 DOSFAT32                2.0 GB     disk3s1
/dev/disk4
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *31.6 GB    disk4
   1:                  Apple_HFS Install macOS Sierra    31.6 GB    disk4s1
/dev/disk5
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     Apple_partition_scheme                        *20.4 MB    disk5
   1:        Apple_partition_map                         32.3 KB    disk5s1
   2:                  Apple_HFS Flash Player            20.4 MB    disk5s2
/dev/disk6
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     Apple_partition_scheme                        *43.5 MB    disk6
   1:        Apple_partition_map                         32.3 KB    disk6s1
   2:                  Apple_HFS A Better Finder Rena... 43.4 MB    disk6s2
/dev/disk7
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            macOS High Sierra P... *204.8 MB   disk7
mac $

You could also try Disk Drill.

https://www.cleverfiles.com/memory-card-recovery-mac.html?gclid=EAIaIQobChMI-L_A rcme2QIVA6ppCh06YgkMEAAYASACEgLyn_D_BwE

Years ago I used an app called PictureRescue, which is available from ProSoft:

https://www.prosofteng.com/picturerescue-photo-recovery-software/

The card from which the files were recovered was corrupted, not accidentally formatted, but PictureRescue was able to pull off images that nothing else could see.

If Data Rescue can't find any files, it appears you have lost your pictures. Does Disk Utility see the card? Can you reformat it?