Hey ciroloma,
In addition to what procyrpto shared, also make sure you’re on the bsc network. MetaMask auto defaults to Ethereum mainnet. Once you are on bsc you’ll want to use import tokens to add bnb if you don’t see bnb.
In this link, check out Luigi’s posts where he shares links and info on how to add bsc network to your wallet. Also keep in mind to always be careful you’re only transferring tokens on the same network and remember to go between networks you’ll need to use a bridge. Hope you find your tokens soon!