Lost 3g and 4g service (on Sprint) a little over a week ago. Called Sprint who said they had tons of calls in my region (S of Philly) after a pretty decent storm went through and that they were working on it. I said ok, I'd give it a couple days. Called them late last week and said I still wasn't getting connected. They checked and I'm about a half mile from a good tower. Signal looked good from their end. We went through a bunch of resets, finally with a total reset. No luck.
Suggestions. I'm on Calkulins E4GT ROM v2.9.2 (admittedly old, but perfectly fine). No real problems to speak of 'till now.
Unfortunately, I'd say flash stock and take it in to a store.
The storm wreaked havoc on my service too, but it was restored. I'd guess someone didn't reprovision the data correctly on Sprint's side, but there's also the chance that service just sucks in your area now. My data with Sprint just disappeared in places where I used to have it.