i lost my macho brace...

[Triv3ls02]

I was Ev training my mudkip with macho brace, and after a battle against a seedot in route 102 the brace vanished and i dont know why, i need help

[Epithet]

Hello @Triv3ls02. My apologies for the inconvenience. 
 

Seedot can have the ability Pickpocket, which can steal the targets item when making contact. What most likely happened is that you encountered a Seedot with that ability and it stole your Macho Brace. 
Since this is how the ability is intended to work, we will not restore your item. 
 

For future reference, please know that if a wild Pokémon steals your item with an ability or move, you can catch that Pokémon and it will be holding the stolen item.

 

If you have further questions, please let me know.