I deleted a file on my 3g that totally killed bluetooth. best way to get it back?

There is no worry now if we lost data. And there are mainly two ways to recover lost data from iphone 4s after accidental restore.Below are the steps about how it work.
Guide 1: Directly Recover from iPhone 4S
Step 1 Connect your iDevice to the computer
Step 2 Scan your iOS device for lost data
Step 3 Preview and recover your data selectively
Guide 2: Recover Previous Data from iTunes Backup from iPhone 4S
Step 1 Choose your Device and Select the Recovery Mode
Step 2 Scan the Backup File of your Device
Step 3 Preview and Recover Lost Data
If you want to recover from iTunes, provided that you have a backup inside iTunes.
www.mobikin.com/ios-recovery/restore-lost-iphone-data-after-upgrading-to-ios-8.html

Try restoring with iTunes. Be sure to backup before to avoid losing important data