My ADA was s stolen from Yoroi Shelley Wallet

In a decentralized system the user is responsible for keeping the tokens safe. That applies to all cryptocurrencies, not just Cardano.
Unfortunately, the support will not be able to retrieve the tokens as nothing can be done. Transactions cannot be rolled back as no one can alter the chain.

That’s why some people are using hardware wallets or more secure options to interact with the network.

I see it like this:

  • Tokens at an exchange wallet > Least secure
  • Tokens in local wallet > more security if we are aware of how to minimize the chance of the computer getting infected
  • Hardware wallet > more security
  • Transactions through CLI while having private keys encrypted on an offline machine where the transactions are signed > most secure

There are also multiple ways of storing the recovery phrases. From keeping it on a hard drive (least secure) to splitting it into multiple chunks and keeping it at different locations (see RAID 5, 6).

Crypto is still a new technology and we must be well informed before investing considerable amounts of money and energy into it.

I think this post explains it nicely:

I’m really sorry for you and I can imagine how you are feeling. If you have any energy left try to research how that might have happened, whether your computers are infected, as if they are it may not stop by stealing just the crypto. Think of bank accounts, personal data, etc…