There are several ways of determining your end inventory.
If you can't do a physical count, you can use the formula: Beginning Inventory + Purchases - Cost of Goods Sold (COGS) = Ending Inventory

You can also use the Gross profit method formula:
Total Cost of Goods Available for Sale (= Beginning Inventory + COGS) - Estimated Cost Of Goods Sold (= Gross Profit x Sales) = Ending Inventory