I got my screws all mixed up.how do i figure out which screw is which?

I was fixing my volume button on my iphone 5 and had to take it apart.long story short i bumped my desk and most of the screws were mixed together and now i can't tell which screw is which. How do i find out the size of the screws and where they belong?

Find another one so that you can guess screw sizes easily…

D/l the app there's an app for everything go to apples web site and d/l the PDF file