In general you should wait a bit. For example we recommend to wait at least 24 hours before accepting an answer to give people from around the globe a chance to have a look at your question. Users on this site are in many different timezones.
Weekends tend to be slower than weekdays, which is why you should expect less interaction with your questions/answers on these days. Nights tend to be slower than days (American nights - I think the majority of active users are from America).
It also takes some time for people to:
- find your question
- read your question
- think about your question
- find relevant sources to underline their points
- write an answer to your question
- fix any formatting issues with their answer
- re-read their answer (for example English is not my first language, which is why I try to re-read everything to have at least fewer mistakes)
- post their answer
In general the Q&A system of StackExchange accepts that some questions may sit unanswered for a looooong time. On WorldBuilding it's relatively rare that questions are unanswered and open for more than maybe a couple hours. We have some questions that require hard-science, mostly about something that has to do with orbital-space-planet stuff that people such as me have no idea about how to even read the question and where you need exact answers with lots of maths and citations from scientific papers and such. If your question is difficult the "think about your question" and "find relevant sources to underline their points" as well as the "write an answer to your question" parts will take a lot longer. We also don't have too many hard-science experts, so the "find your question" part is likely more difficult, too.
You can see a list of all questions that are currently unanswered without any answers here. As of writing this the oldest one in this category is Creating a Scientifically Semi-Valid Pseudo-Arthropod Primate Part 1: Pseudo-Dragonfly Wing Rib Muscles - which is roughly three days old. The oldest one without an upvoted answer is Physiological adaptation of life on a planet orbiting a red giant., which is roughly a week old (but there are two answers and a bunch of comments). You can see this list here.
Other sites sometimes have questions that require certain expert knowledge in mostly-unknown fields that sit around for years until someone goes through some of the more obscure tags and the unanswered tabs. For example on RPG.SE I have seen someone ask about a very old game whose rules were not available on the internet whether something was written in a certain edition of the printed books the way it was in his or if his one was a misprint - that means someone has to have the same edition of the rare, very old book and see the question on this specific site and have the time/intention to actually write an answer. Who knows how long it will sit unanswered?
It's actually pretty rare that questions are deleted. If it's downvoted, closed as off-topic (meaning it was "on hold" for a week without an edit from the original querent), hasn't seen activity for a while in closed state and doesn't have an upvoted answer it can automatically be deleted. Or if it's spam/rude/abusive and someone asks an elected moderator to delete it/ a few people with very, very high reputation think it should be deleted because it's defacing the site. Enough (I think 6 or so?) people flagging it as spam would also delete it. Each spam flag also instantly counts as a -1 without any rep that the flagger would have to use.
If your question has been unanswered and you have the required reputation of 75 for the set bounties privilege you can put a bounty on your question to bump it to the top of the frontpage and have it in the special featured tab for a week. Of course using 50 of your 75 reputation to bump your question is pretty hard, which is why you could also first ask in the chat room (requires 20 rep) if someone can answer that. And if your question has really been sitting unanswered for a while maybe the regulars there can take a look to see if they can improve the question a bit, brainstorm with you - or use some of their rep for a bounty. (You shouldn't necessarily expect the last one, but for example around christmas we had a Holiday Bountapalooza - maybe someone is willing to help you out.)