1) Craft any tool or armor. (Flint and Steel, Bows, and Shears also work)
2) The crafting table should display the number of the specified tool in your inventory under the items name (as long as the item hasn't been damaged)
3) Use the tool or armor until the green damage bar appears under the items icon.(Any level of damage will work)
4) Go back to the crafting table and look for that items recipe.
5) Now that your tool or armor has even a tad bit of damage, the crafting table won't recognize it and will revert to telling you that you have 0 of that specified item even though it is in your hand. Tested in 0.6.1 on a kindle fire.
Duplicate of MCPE-480, please use the search function to see if your bug has already been submitted. Currently over 56% of tickets are being closed as duplicate.