How to Get Deleted Numbers Back on a Samsung Phone

Step1: Go to Contacts > Menu > Manage Contacts.

Step2: Tap Import or export contacts > Import. If any contacts are stored on your SIM card or internal memory, you’ll see those sources in the list.
Then Select the source to retrieve the contacts from, then tap Import.

Credit : https://www.lifewire.com/find-deleted-phone-numbers-on-android-8681908