How do I reverse an iPhone software update?

You do not reverse an upgrade at all.

Apple does not support downgrading firmware, thus there is no official way to do so. You can use Google to search for ways to do so, but such cannot be discussed here per this forum's terms of use. Bear in mind, even if you were to successfully downgrade, you'll be creating a whole host of new problems. Since the iPhone is not designed as a stand-alone device, your best bet is to purchase a new computer. iPhone REQUIRES regular syncing with a computer.

You can sync as many devices as you want to the same iTunes account. However, in your case, create another user login on your partner's computer for you, copy your entire iTunes library to this new user account, as well as contacts & other important data, and you should be good to go. Your existing iTunes content will be erased from your phone upon that first sync with a new computer, but if you copy your library, you'll simply sync it all back to your phone.

You're welcome.

Not sure if you can help, but my husband's iphone hadnt been synced with itunes since Jan 12.

Connected 2nite as we wanted to back up his contacts and it upgraded to the new software version. However now its gone back to the way it was in January, ie all the contacts, notes, messages, photos, everything, that he has added to the phone since this time are no longer there.

I presume I didnt do a backup before the upgrade that has caused this issue. Is there anyway to recover this information?

I need a solution to fix this.

Any help greatly appreciated.

You do if it's 10.3.2 and it messed the phone up!