If I didn't get a reply after sending a message, I would just wait for a while. Maybe the person is busy or hasn't seen my message yet. I think it's polite to give them some time to respond. Sometimes people forget and reply later, so I try not to worry about it too much.

If I really need an answer, I might send a follow-up message. Sometimes messages get missed or not delivered. I would keep my reminder polite and not too pushy, just in case they are busy or didn't see my first message.

If I still don't get a reply and it's urgent, I might try calling them or using another app to contact them. Sometimes there are technical problems with messages. If it's really important, talking face-to-face can be better.

If the message wasn't important, I would just move on and not worry about it. Not everyone has to reply, and I don't want to waste time waiting for a response. I would just focus on other things instead.