If you are trying to understand some riddle and find the answer for it, it shows that you are in some situation in your waking life where you do not understand what is going on. The riddle could also denote to some situation in which you are feeling lost and also looking for the right solution. Sometimes the riddle is simply the reflection if the stress the dreamer is suffering from or have difficulties to separate unnecessary thoughts during the sleep.
Riddle dream meaning
Read more about dreaming of Riddle in other dream meanings interpretations.