out of ideas

What if we refute all our ideas with criticism, and can't think of another?

You can always think of an idea! If you don't have a better idea, then flip a coin to decide. Do something random. Or just go to sleep and worry about it later. Or go play video games and ignore it. If you don't want to ignore it, OK, sounds like you have a better idea; do that. It's not too hard to come up with some minimal thing. It might not accomplish everything you wanted, but at least you can get on with life and won't be totally stuck.

What if you want a good idea, and can't think of any? Start a discussion with other people. Ask for help. Read books on the topic. Read vaguely related books. Do something else, then come back to it later. Search on Google. There's always something you can do that has some possibility of turning out helpful.