Try to clear cash.
http://www.abantecart.com/ecommerce-documentation/57-admin-user-manual/system/cacheThere is no way something would be missing unless somebody or something deleted your data or restored older database from backup.
Some steps to check:
1. Run simple select in your database to see if your products are there:
select * from ac_products; (note: you need to change ac_products to [prefix]_products with your prefix used at installation)
See if your products that you created are there.
2. Check that you use correct URL and you do not access some other store.
3. If you have hosting service or someone else working with you, check if there was no back up restore done at some point.