This Quickcheck – “What to do when all we produce are useless ideas?” is a microtool that you pull out as a kind of checklist whenever you feel that all the ideas generated are totally useless. Basically, you should not let this discourage you even slightly. Creativity is not a thing that always happens at the same good level. Creative new solutions often need a lot of patience, especially when complex challenges need to be solved.
Moreover, an idea that is useless today can be a very valuable and useful idea tomorrow, possibly for a completely different challenge. Every failure is always also a step on the way to a solution.
But there are also very specific things you can do immediately to increase the likelihood of producing very useful and good ideas again.