Have you looked up how to use particular? Or were you hoping you'd figure it out intuitively?
Nobody can know. We have no idea what your parameters are actually set to and as Dave said, Particular itself is a complex plug-in with more than 2000 parameters, so it takes time to learn and master.
If you have watched this: Red Giant - RGTV - Getting Started and you still are having problems then watch the rest of the getting started series on Particular from Red Giant TV. If you still can't get anything to work then give us a complete project description and list of steps you took to get to where you were stuck. I have a feeling you are missing the basics of how AE works with effects more than you are missing how Particular works with AE.