I can't find my city, but it was saved! - Complete the tutorial phase in the 'new' city, then in 'Settings' log in to either Facebook, Game Center or Google Play (according to which you saved it with originally) to restore a saved city.
I can't sign in, the log in buttons are missing! - Complete the tutorial - i.e. until you've built the City Hall - then the connection options will magically appear in your game settings
Can I delete my city and start over? - Sorry Mayor, your city is for keeps! Try rearranging your buildings or re-drawing your roads if you need a change, and remember you could get some of your Simoleons back for bulldozing purchased buildings!
Can I delete my saved cities from Facebook, Game Center or Google Play? - There's no way to delete those previous saves, sorry! It's a security feature to make sure you can play across your devices safely.
My advisors are talking the wrong language! - Don't worry, it's Simlish! If what they're saying is important, there will always be subtitles for you to understand them.
I can't bulldoze my factories! - Yes you can! Press and hold the building to highlight it, then tap the bulldozer icon that appears on the right of the screen.
I didn't get my Golden Key after the Cargo Ship left! - Make sure you tap 'Cast Off' and have seen the ship leaving the port - only then you will receive your key reward!
I didn't get my item back when I cancelled my Trade Depot sale! - Be very sure when you cancel a sale, as the item will be lost forever! As City Storage has limited capacity, it's not possible for the item to be returned to you.
I'm the right level, why hasn't an item unlocked? - Does the item's Commercial Building need upgrading? Check the star level under 'Requirements' - one star means an upgrade to level one is necessary.