Boy, I really feel for you. I hope this city is not lost, after all the hassle you've gone through. My guess (and probably yours) is that when you lost the connection, it corrupted data somewhere. If that somewhere was on the server, it may be lost forever.
It looks like you've tried everything, there are only a couple of things I can think of beyond what you've already done. First, try renaming the UserData folder (or move its contents to a different location) and relaunching. It should build a new one that might work. Second, try the recovery tool. C:\Program Files (x86)\Origin Games\SimCity\SimCityRecovery\SimCityRecovery.exe. The recovery tool will not touch the UserData folder, so try both.
If this doesn't work, I'll try to go online and see if I can see your city. I don't have the complete edition, so I wouldn't be able to load it, but it might let me visit.
I know when the game first came out they had a huge problem with the servers not handling the load and were able to roll back some of the cities. If all else fails, you could try contacting support and see if you can get someone to do it for yours. The problem, ofc, is this game is no longer actively supported or updated, so that may not be an option anymore.