If you're able to get a hardline connection to your modem via Ethernet, visit http://192.168.1.1/ from your web browser, and then log in with one of the two sets of credentials below:
From there you'll be able to customize your Wireless settings and also view your security key. The above should work with any modem / router provided by Verizon.
Worst case, reset your modem using the reset button (hold it down for 30 seconds). If your network name (SSID) and password are on a sticker on the router, the reset will revert the network name and password back to what is seen on the sticker. You can also change it using the Web address I provided above to what it was before.