Hi Farlap,
We understand you're trying to recover contacts. We're happy to help.
To get started, you'll want to determine if you had your contacts synced anywhere or if they were just stored directly to the device.
To see if they were synced to iCloud, go to the iCloud website and check the Contacts section to see if anything is showing. If you do have contacts there, you can sync them to your iPhone by going to Settings > your name at the top > iCloud, and turn the Contacts option on. If it's already on, turn if off for a few seconds, then back on to refresh the sync.
To see if you had them synced to a third-party email account, go to your mail providers website, log in, and check the contacts section. If you do have contacts there, you can sync them to your iPhone by going to Settings > Contacts > Accounts > Add Account. If you already have that email account added and the contacts option on, turn it off for a few seconds, then back on to refresh the sync.
If you do not have your contacts synced anywhere and they were just stored directly on the device you may be able to recover them from a backup. You'll want to check if you have a backup that was done at a day/time the contacts were still on the device. you can use these steps to check for recent backups: Locate backups of your iPhone, iPad, and iPod touch
If you do have a backup available that was done when the contacts were still on the device, you can use these steps to restore it: Restore your iPhone, iPad, or iPod touch from a backup
Keep in mind when you restore a backup, it will restore the device to exactly as it was at that time. So for example if you restore a backup that was done on Thursday, anything you've added/changed on the device from the time of that backup until now will be removed.
We hope this helps. Take care!