If you've built 10 products and hot no-where then perhaps your strategy is a bad one.

And yes, building something then looking for customers is a bad strategy.

I strongly recommend you spend the next month finding a market. Don't start building the next product until you have made sales. If someone says "I'd pay for something that does x" then ask for a deposit. If they say "no", then keep looking.

And no, paid advertising is not the solution. That doesn't get you users (at this point). At this point you need to talk to people.