How to unlock broken iPhone 5c?
What do you mean by "I don't know how to unlock it and even if I did, I can't: half of the screen looks like a matrix" ?

Do you mean you actually do know how to unlock it but can't because the screen is damaged? Or do you mean you can't because you've forgotten your passcode? Or do you mean something else?

We may be able to help if you provide full details of your situation and what you've already tried.

For example, have you tried any of the following:


Restarting your device by holding down both the power button and pressing down on where the home button should be for at least 10 secs until the Apple logo appears?
Double tapping on the slider to see what happens?
Connecting your device to your computer after launching iTunes?
Connecting your device to your computer and running your photo software to see if you can transfer your photos?


Also, is your device set up to use photo stream on iCloud? If so, your photos may already be accessible via iCloud from another device, so you may not need to transfer them from the iPhone. 

Please provide as much info as you can.