If your campaign has been declined, you can resubmit a new one for approval. Be sure to check this page in case your campaign is a restricted category. Your campaign won't be approved if you fall under one of the restricted category under any circumstances.
Below are examples of campaigns with a clear goal, and creators can easily get an idea of what the brand is looking for.
Feel free to resubmit your campaign again and use one of the samples below as a template to model off of.