Thanks for writing. Squash will abort their young fruits if the flowers aren't pollinated, so check to see if you have bees, butterflies, or other pollinating insects in your yard. If not, try planting some flowers near your squash to help lure the pollinators to your zucchini.
The plants will also abort their young fruits in harsh conditions --- if it's too wet or dry or hot or cold, for example. So happily, if this is the case, the problem should correct itself once the weather conditions even out (or you help make up for them if it's too dry in your area).
---Justin, Senior Garden Editor, BHG.com