all my contacts disappeared from the address book, but if i go in to messages i can see the names and same in phone.
if i via phone go to address book, the address book reappears for a little while and then disappears.
so my contacts are in there, but lost in cyber space - how to get them out.
try to get them backed up to icloud but i cant switch my iCloud address book switch to on
wish i had not upgraded, what to do
It's in C:. But actually you can not open and access it. It is just a security file inside your computer. But you could still recover lost contacts with the help of a third-party tool. You can get the tool here: http://www.wondershare.com/data-recovery/iphone-data-recovery.html It can easily recover your lost contacts by extracting files from iTunes backup of your device, and it provides you with a trial version which allows you to check whether the found contacts are what you want or not. It's as effective as you can imagine.
May be you are working in Windows, aren't you? As far as I know, syncing iOS 5 with iTunes recommends backing up contacts, calendars, mail accounts to iCloud. If you have iOS 5 before upgrading to iOS 6, I think you have made a wrong choice. You should put all your data on the cloud. No matter which device is in your hand, your data will never get lost.
You said you have lost your contacts. Do you have backed up your device before? If you have backed up your device to your computer, you can bring them back.
And if you have using iOS with Windows, although it works and nothing seriously happens, I recommend to buy a Mac. You will see that your life with your devices will become so easy and joyful. Albeit that Macs are more and more reliable, safer, stronger and easier to work than regular PCs.