I recently upgraded to ios7 and now my PC is not recognizing my iphone

I am having several problems. I recently upgraded to ios7 and now my PC (Windows 7) is not recognizing my iphone. 1) I am getting an error message when itunes opens: "Itunes could not connect to the iphone because it is locked with a passcode. You must enter your passcode on the iphone before it can be used with itunes." How did it get locked and how do I unlock it without losing my data? What do they mean by passcode? I don't have a 4-number code to get into my iphone activated. In fact, I've never had a passcode.

2) I cannot download my photos from my iphone onto my computer because my computer doesn't recognize my iphone. In other words, my iphone does not show up on my computer (no iphone icon, no DCIM folder).

3) This is a separate issue but it is also very confusing: I went online to check my iCloud and I cannot see any data (icloud.com). But I know that I set up iCloud when I upgraded to ios7 and it backs up my data every night. What am I doing wrong, am I unable to see my data and photos?

Why is this happening? It was bad enough that when I upgraded to ios7, I lost my Notes - I have no idea why they didn't return. But now essentially my iphone is not recognized when connected to my computer and this is very frustrating. I have read numerous previous postings regarding downloading photos onto the PC and regarding this passcode error and cannot find a resolution, so I would appreciate any help.