Talking makes so many simultaneous demands. Among other things, we have to think about what we want to express, choose the words that will do that job, control our speech muscles to make the tiny movements needed to say the words. Imagine these demands on a baby or toddler. Every one of these skills is new. Couple that with big feelings, tiredness, etc and it is not surprising that some children struggle to communicate with words, even though you have seen them do it before!
Ask yourself, “Does my child ALWAYS struggle to talk independently, or only sometimes?” If it’s only sometimes, perhaps they are tired, emotional, overwhelmed, or unwell. However, if you have to prompt them to speak most of the time, maybe check basic milestones, or check in with your paediatrician / a speech therapist – it may be a case of late talking or speech / language delay.