Turkey first started the process of applying to join the EU in 1987. In order to join the EU, there are 33 "chapters" of standards which a country must meet.
In the 29 years between 1987 and the referendum, Turkey had managed to complete just one of these chapters.
Turkey is decades (if not over a century) away from completing the other 32 chapters.
Even if Turkey completes all 33 chapters, that is still no guarantee that they will join. Every EU member has a unilateral veto over any new membership application.
Since the referendum, Turkey has experienced an attempted military coup. In itself, this indicates that Turkey is nowhere near ready to join the EU. But the subsequent heavy handed behaviour of the Turkish Government against suspected collaborators guarantees that they will not be joining soon.