Samsung's have their own contacts app and I think their own way to backup to the cloud. Seems kind of redundant but I usually use Gmail apps rather than the Samsung ones so not tied to a particular manufacturer's software ecosystem.You can also use the Coolmuster Android Data Recovery progam to do recover your deleted contacts from Samsung Galaxy phone.
Once lost data on your Samsung cell phones,please stop or add new data to mobile phones,in order to avoid those lost data is covered by overwriting.To get lost contacts back from Samsung Galaxy phone,you need to use a Android Samsung Contact Recovery software,they can scan and perform contacts from Samsung Galaxy,then you can use the contact recovery restore deleted contacts on Galaxy phones,and save all lost or deleted contacts on your computer,make sure all restored contacts never lost on the computer.What’s more,the Android data recovery: Samsung contacts recovery not only can help you recover Samsung deleted contacts,but also allows you retrieve other lost data or deleted files from Galaxy,such as text messages, photos and video. It works well with most of popular Samsung Galaxy smartphones,like Galaxy S5/S4/S3, Galxy Note, Galaxy Ace,ect.
More resource reference:
Hope that helps
here is a solution for your reference:
Samsung Data Recovery is specially designed to recover all data including photos, contacts, text messages, music and more on all Samsung devices. It supports all Samsung phones and tablets running Android 4.4 and under, even Samsung Galaxy S5, Galaxy Note 3.
Well, if you have a backup files somewhere else, then you can regain the lost data from the backup files. For sumsung devices, kies is a excellent backup tool. Still, if you did not backed up before, then this video might be helpful for you.