Why isn't my iPhone getting service?

I was putting my phone in and out of air plane mode a little bit to save battery because I was in an area that had a very poor signal. Now I have turned airplane mode off and no matter where I'm I have "No Service" on the service bar. I can get Wi-Fi but not cell service or 3G (I have Verizon)

Just leave the phone off for a bit (15 minutes) then turn it back on.
my iphone does this alot.