The "seek helpseek help" answers are definitely correct. It is highly unlikely that you are the first person to ever encounter a particular problem.
But as a though experiment, what if there is no help? What if you must solve the problem on your own? The most important problem solving ability is the ability to identify and challenge your own assumptions. If you can enumerate your assumptions about a problem one-by-one and eliminate each in turn, you will eventually come upon the errant assumption and new possibilities for a solution will open up as a result.
(By the way, this is also the best approach when you can't see an answer to a problem you get in a job interview. Verbally list out your assumptions, and determine which one is wrong and then re-attack the problem. Almost all "trick questions" are based upon natural yet faulty assumptions).