how to repair broken screen of i phone 5 from where do i buy te screen?

You don't buy the screen. Apple does not sell parts.

Apple also does not repair iPhones, they replace them. Make an appointment at the genius bar of your local Apple Store. An out of warranty replacement phone will cost you US$229.

Vienna Austria or Vienna VA

https://locate.apple.com/country

Look it up, call the location and ask.

As has already been explained by Tim

Apple does not repair any iPhones all are replaced either under warranty or at an out of warranty exchange price

Damage is NOT covered by the warranty

The price for an exchange iPhone 5 is Euros 229 over the counter

If you have an Apple Store in Vienna take there for service

If anyone else tampers with the iPhone it will void the warranty and Apple will refuse any future service on the iPhone

http://support.apple.com/kb/index?page=servicefaq&geo=United_Kingdom&product=iph one

pick Austria from the drop down country menu for all your service options

If you take it to Apple they will replace the phone for $229 US, probably something equivalent in Austria. I'm sure you can find a local phone repair who will replace the screen for less, however this will invalidate the warranty on the phone. You also cannot get a recommendation for an independent repair shop in an Apple hosted forum, but I'm sure Google can help you locate one if you want to follow that option.

Apple will give you a replacement immediately. You would have to ask a local repair shop how long they will take, however, it shouldn't be more than an hour or two unless they are backlogged.

You would be better off dealing with an Apple store for replacement, the screen and digitizer are glued together on the iPhone 5 and replacement is likely to be pretty close to the cost of replacing the whole unit with Apple, $229 (US).