brahim Tanjawi , Find links below to help in the changing of screen on your device link #1 video and link #2 guide, 3rd link is just 1 of many sites you can get replacement screen, you can do a google search for better pricing. Good luck.
I hope this helped you out, if so let me know by pressing the helpful button.
https://www.youtube.com/watch?v=XFDI3bKmYmY
http://www.formymobile.co.uk/s5570disassembly.php#.WHJAHdIrJxA
https://www.aliexpress.com/store/product/For-Samsung-Galaxy-Mini-S5570-New-LCD-Display-Screen-Panel-Monitor-Repair-Part-Fix-Replacement-FREE/714382_2030120416.html