Restore iPhone from previous backup?

A message popped up on itunes saying in order to update my software I must restore & back up my iphone.although once I had restored it, it had got frozen on the "connected to itunes screen" while it was backing up all my previous data. I then stupidly clicked back up iphone, again in order to make it work although it just erased all my data and set my iphone up as new.

Therefore how do I load my iphone with the previous back up (before I accidentally backed it up again)? As it has all my photos, texts etc. On it.

Just a note I've seen websites saying you can find previous back ups on,
Windows 7 and Vista:
C:\Users\YOURUSERNAME\AppData\Roaming\… Computer\MobileSync\Backup
Although I'm on windows 7 and this "AppData" which contains these folders is not on my computer at all.

Its all nothing but restore your os and backup your files from itunes only the files… Just don't restore the apps… If you backup the apps sometimes it may lead dead… Sometimes it may happen one of my friend mobile has gone like the same way… If the appdata is not in your pc means you didn't take the backup or yours windows dosen't save the backup