Can't find research articles to answer your PICO(T) question? Think about the topic behind the question, and ask yourself: Why not?
If no researcher has done a research study about your topic, then there are no articles to find. You can't find it if it doesn't exist!
If initial searches find articles, but result lists disappear when you add date limiters, it's likely there is no CURRENT research about your topic. Like many other things, research is trendy. Your topic might have been well researched several years ago, but it's not "hot" in the current literature.
Is the outcome measurable?
Is it possible to measure it? How? Using what indicator / instrument / measurement?
Is it reasonable to measure it? Would it take years/decades to accumulate the data? Is the population accessible/available to researchers?
Is the outcome common knowledge? Topic examples: Does breast feeding improve immune system development? Does hand washing decrease the spread of infectious disease?
Would a researcher have ethical issues to consider in order to explore this topic? Topic example: Do infant sleep positions impact the incidence of SIDS? Directives relating to this topic come from professional judgments based on historical data about SIDS; it would be unethical and illegal for a researcher to risk infant death by adjusting sleep position to one that has been associated with a high incidence of SIDS.
If your question isn't answerable, it can usually be adjusted.
Don't abandon all the work you've done! If you're finding articles but they aren't the ones you hoped to find, review your results before making a dramatic topic change. You can probably formulate a new PICO(T) question based on studies you have already found.
Talk with your instructor to brainstorm ideas about how you can use your findings to adjust your question so it is answerable in the literature.