Am I able to reactivate my phone after reporting it stolen?

You have told us nothing about the iPhone's state. For example:

• Did you have Find My iPhone engaged?
• Did Find My iPhone actually erase the iPhone?
• Did you report the iPhone stolen to your cellular carrier?

This article may help. If you do Settings > General > Reset > Erase All Content and Settings and enter the appropriate data (e.g., your Apple ID and password), presumably you can re-activate it given your cellular carrier allows this.

If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support