Thanks for all of your honest answers. Yes, it is true, it was really stupid not so set any stop loss orders! The reason for this damn decision was my bad experience while investing in XML. I was stopped out several times even when setting the stop loss 25% under the price. In the end I had a nice profit but it could have been much more -> welcome greed. So I made this bad decision not so use stop loss orders anymore trading crypto due to the high volatility. Another point is that I got influenced by many people on this forum and the internet in general who constantly tell to hold, which is for a crypto newbie - looking back - definitely not the best advice if you are overinvested like me.
However, I am relatively new to this market and haven't expected that there might be so many ups and downs in such a short period of time. At the moment I am only in green with LTC, because on the high I have switched many positions instead of taking profits into BTC or USDT. So now I have liquidated a part of my investments into BTC and USDT. Thanks again for all your ideas how to handle this!