NOTE: You can check this thread for instructions on how to back up data on the phone.

Restore Contacts from SD Storage:

  1. Open “Contacts
  2. Tap “Menu
  3. Go to “Settings” and access “Contacts to display
  4. Switch to “All contacts
  5. Tap “Import/export contacts” > “Import from SD Card
  6. Tap “OK

Restore Media Files from SD Storage:

  1. Launch “My Files
  2. Access “SD Card
  3. Tap “Menu” > “Edit
  4. Tick the boxes associated with the media files you want to restore
  5. Tap “Menu” > “Move
  6. Select “Internal storage” > “Move here
  7. Alternatively tap “Create folder” and select the folder
  8. Tap “Move here

Restore Media Files form a Windows PC:

  1. Connect the Android phone to the computer via USB
  2. On the phone, enable “File Transfer” / “Media device” when prompted or from the Notification area
  3. Launch the File Explorer on the computer
  4. Locate the media backup files and copy them
  5. Transfer the files to the phone storage, preferably in the folders from where they originate
  6. Once done, eject the phone storage and safely disconnect the phone from the USB cord

See More: Samsung Galaxy J4 Core: Restore Contacts and Media Files