You may find this
Microsoft FAQ page useful. Basically:
1. If you were in Developer Preview but un-enrolled from it, then check for updates with Developer preview activated, install any update, then deactivate DevPrev, then check for new updates.
2. If not, then you could try using the Lumia Software Recovery Tool or the Windows Phone Recovery Tool. Links to the software are included in that page.
You may want to create a Windows Central account to respond to this thread.
Here's more
information about the error.