If you are trying to get back contacts that were previously on your device, then first try backing up your device. This will help you ensure that you are able to access your contacts if you need to. Depending on the type of device you have, there are a variety of ways to back up your device. For example, iOS devices can be backed up through iCloud, while Android devices can be backed up through Google Drive.
Once you have backed up your device, you will be able to access your old contacts through the backup. If you don't have any backups, then you can try to access the contacts through your device's manufacturer. For example, if you have an iPhone, then you may be able to access your contacts through your iCloud account.
If you have tried all of these methods and still cannot access your old contacts, then you may need to contact a professional who can assist you. They will be able to help you access your contacts and get them back to your device.