You should let him contact you first and then move forward from there.
If he wants to work on the relationship and you feel the same way, then the both of you need to get reacquainted and start spending some quality time getting to know each other better.
If he doesn’t want to work on the relationship, then you should accept that and avoid trying to force anything.
You may be able to win him over if you were to try forcing the relationship to work, but then, the relationship would be imbalanced when it comes to who holds the power.
This means that it would only be a matter of time before the relationship would suffer again from a lack of continuity and emotional investment.
You shouldn’t ask him why he unfollowed you on social media.
Trying to get an explanation out of him isn’t going to help your situation. If anything, you would only give attention to the fact that he has issues with you and this relationship.