In june & July I bought Digibyte & Stratis & Siacoin with all my bitcoins, till now I lost almost 80%
What can I do, HOLD or Sell or What!
Depends. What alcoins were they? A lot of people sold altcoins in hoping for additional bitcoin gold coins when the fork happens. If they are reputable altcoins, hold them and they should go back up.
Second this suggestion, selling at such a loss with reputable altcoins would be a bad decision. As I'm sure those that sold their bitcoins and litcoins, etc during the crash a few years ago will attest, hodling is best if you believe in the tech.