Clash-of-clans – village overwritten

• First, launch iTunes on the computer that your apps are stored on.
• Go to the Apps section of iTunes
• Right-click on Clash of Clans
• Click on Get Info
• Summary tab is where you would see 'Account Name.' It would be the apple ID that was used to purchase the app.

And it would probably be your gamecenter log-in as well that has your village saved. Now so as to migrate from one device to another, simply go to Settings > Game Center > Click on the AppleID and voila.

Hope this helps.

If you have already used your one sync, then you are kind of stuck. When switching devices, they allow you only one sync. This is for security reasons, but it kind of acts as an inconvenience here. There is almost no way to get your account synced after that. I would recommend contacting Supercell if you are desperate.