lumia 640xl showing Sad Emo

In file manager I found "main os" files.. so, deleted the "App Data" or something else. :-P

after that every thing gone to blank. at 1st the tiles, then Lock Screen. In panic, I restarted the phone. that's all..

now my Lumia 640xl only shows the startup windows logo, then it switch off automaticly.

what to do now..?

then I found some tricks to reboot, using lock key and volume keys combination ..

then the bearing screen appeared, after that a sad Emo.

it happening again and again..

what to do.?