You can check your online call/text records to see who you last contacted - that may help you figure out where you last used it. You can suspend your line so the phone will not work, and I would also call Verizon and report it lost so that no one else can activate it for their use.
The sooner you report it, the less you will be liable for anyone using it between when you lost it and now. You can check the activity on line to see if it has been used since you lost it.
Yes, it will still cost $$ to replace it with insurance, but much less than a new phone would cost you.