I honestly don't know if you can get them back that way. He should have advised you to backup or sync to the Samsung Kies program on pc, or now the Samsung Smart Switch pc backup program, Kies is being phased out I think.
(the Smart Switch app is only for transferring from old to new Samsung devices, iirc)
However, Samsung contacts are usually either Google (cloud) Contacts, Samsung (cloud) Contacts, device contacts only synced to Kies on a pc, and some few contacts can be stored on the sim as a number and name only.
Hopefully if you haven't tried yet, turn master sync on and go to Accounts - Google - and check the Contacts box.
Same for Samsung Contacts. If you don't remember setting up a Samsung account or can't remember the log in details, the local Samsung. com site is helpful in prompting you back to your account.
Later you could use Merge to move all Samsung and device contacts to the Google account, which is the safest thing.