This is a problem with 1.6 versions of the game where tools will have no durability after being dropped. This topic has been merged to make for fewer topics.

I recently started using this pack DokuCraft and noticed that every once in a while my perfectly fine tools will randomly disappear out of my hand and removed itself from the game entirely. I had my Diamond pick and was hacking away at a wall (This was a fresh made pick), and it disappeared immediately after it destroyed one block. Has this happened to anyone else? Is there a way to prevent this? Is it the game or the pack? Please help

Items after being dropped, then picked back up, will disappear on next use. So don't drop your items, and don't die until next patch lol
I'd advise against using diamond items as well

It is a known issue. Patience and it will be fixed in due time.