Did you Reset - Erase all Content and Settings - to start over as if it is a new phone. If it continues to have problems, take it to an Apple Store if you have one in a reasonable distance, or call Apple customer support.
I am sorry to hear about the phone crashing and not picking up Verizon signal, JenGfer. Let’s make sure we get your phone up and running again. When did this problem start happening with the phone crashing? How long have you not been able to connect to the mobile network? Is it happening in more then one location (outside a 5 mile radius). Please share more details.
Let’s check to make sure your carrier settings are up to date. Click here for the steps: http://apple.co/1XboGkJ . Also please ensure you have the most recent software installed on the iPhone. Click here: http://apple.co/1QKw1nH