if you cannot solve a problem, you can do a lot of things on your own.
look at correct submissions of your problem and figure out what they do
try to split the problem into subproblems and solve them one after another
try an even easier problem. If you are stuck for a long time, you may want to move on. Being stuck for 10+ minutes is enough for a beginner to move on. If you are advanced, 30-60+ minutes is probably a better estimate. It really depends though
use Google or AIs to help. For example, my goto AI is phind.com . Be aware that AIs can be bad sometimes (they sometimes lie with full conviction), but asking them to explain an easy solution usually works fine. Here is what I would have asked the AI if I were you: