I mistakenly changed system properties of android

I have an old Karbonn Titanium Octane with android 4.2.2 . As it was dead I flashed it. And I rooted it using KingoRoot android app because of low battery in a few minutes. Now I want to install an app that requires android 5.0 So, I installed BuildProp Editor and then changed the android version (5.0) with the corresponding android sdk version / api level (21). Now every app is not working. What I can do Now!!! The whole specifications of the device is in the image.Click Here to open image.