"System has been modified please contact the manufacturer, thank you!" message appears on the lock screen of SKK Mobile Prime

My phone is an SKK Mobile Prime on Android 4.2.2. I accidentally deleted my Android device manager and other folders on my phone that I thought were not useful at all. After that, this message appeared on my lock screen: > System has been modified please contact the manufacturer, thank you! I can't unlock my phone without having to touch the upper portion of the screen where it will show you the time, date, and the setting icon for your phone. So, after doing so, I tap the "back" button or "home" just to see the phone menu and do stuff. I know something on those deleted folders has something to do with this. This has been my problem for 4 months already. I've been to different technicians, but all they do is charge me overprice. Can somebody help me?