Car completely dead, disconnected/reconnected the battery and it was fine.
 

Today I went to get lunch in my car and it was completely dead the doors would not open or anything. I checked I have not left anything on. I opened the bonnet/hood disconnected the battery and then reconnected it and the car was completely fine.

Has anyone had this problem before, or know what it might be? The battery terminals seemed tight I cannot think of what else would cause the car to appear completely dead when the battery was good.

You probably solved the problem when you reconnected. I've dealt with similar issues before, and it's usually a corroded terminal or terminal clamp that causes enough separation and the vibration while driving breaks the battery connection, car keeps driving on the alternator alone, and is dead when you go back out to start it up. Re-seating the connector corrects it.

Cool thanks, Ill tighten up the terminals. Probably the new suspension putting more pressure on the car.

If you don't stop the corrosion, it's going to happen again :) Dielectric grease goes a long way toward preventing any issues at all.