I'm sorry about what happened. The luggage is lost and they are usually found. In Europe, about 8 bags per thousand are mishandled and, according to the statistics of the Association of European Airlines, 85% of baggage reported as lost is returned to their owners within 48 hours. There is a good chance that your bag will be lost and that it will be returned soon. However, some bags are lost or stolen permanently, about 7% in the world.
If your bag is permanently lost, you are entitled to compensation even if it can be difficult to prove what has been lost. If you have taken out travel insurance, contact your insurance company immediately as cover for delayed or lost luggage is usually part of your policy.
This is obviously too late for the moment, but never save valuables, money, electronics, etc. with me in a small carry-on. Your wallet is definitely something you want to keep with you on board.
Sometimes people take the wrong bag when removing luggage. You can decorate your bag to make it more distinctive, to reduce the risk of this happening, but most people will return it if it happens (after all, they want their own bag instead).