There isn't enough information here for anyone to diagnose this yet.

When you say the products have been "re-activated," what exactly do you mean, and where are you seeing them as active?

A few things we would need to know:

1. Are the ASINs showing Active in Manage All Inventory?

2. Is there positive, available inventory on each SKU?

3. Are these FBA or FBM offers?

4. If FBA, does Amazon show inventory as Available, or is it Reserved/FC Transfer/Processing?

5. If FBM, is the quantity actually greater than zero and is your shipping template active?

6. Are there any errors, suppressed-listing notices, compliance warnings, or approval requirements showing for the ASINs?

7. When you open the actual Amazon product page, is there no offer at all, or is your offer available under "See All Buying Options" but you simply don't have the Featured Offer/Buy Box?

8. How long ago were the products reactivated? Catalog changes don't always propagate immediately.

9. Are these your own Brand Registered products or products from another brand?

If you can post one ASIN and a screenshot of what you're seeing in Manage All Inventory, people here can probably give you much better guidance.

Right now, "Seller Central says it's for sale but I can't see it on the buyer side" could describe several completely different issues.