Q: Updated my 4s to iOS 8.3 and now the blue tooth won't connect to anything and also it's not recognised by other divides, what's wrong,

Hey there Simonhill14,

It sounds like your Bluetooth function is not working properly after updating to iOS 8.3. I would use the troubleshooting in the following article to help you troubleshoot the issue you are having here, named:

iOS: Troubleshooting Bluetooth connections

Let me know how that goes.

Thank you for using Apple Support Communities.

Regards,

Sterling

Thanks for the update. I would next backup your device to iTunes, then restore it as new and verify that it works. 

How to erase your iOS device and then set it up as a new device or restore it from backups

If it does, then restore your backup to either verify it still works and the software just needed reinstalled, or isolate the issue to the backup file itself. 

My apologies, I provided the incorrect article to you to restore the device as new. The method in the last article doesnt reinstall the iOS software, it just erases data and settings. Try one more restore but this time use iTunes outlined in this article:

Use iTunes to restore your iPhone, iPad, or iPod to factory settings

If on the off chance that the issue does still persist, then I would next recommend that you reach out to Apple and setup service for your phone:

iPhone Other Repair Options