Ok so recently i changed my m4 aqua display(bought from ebay)
It started on.When i was unlocking my phone the display switched off but touchscreen still working, Its not a sowtware problem because i reinstalled fresh copy of android trough pc companion. Later i installed same old display and still the same problem. Sound touch vibration working but display not showing... i read that it may be a backlight problem that it stopped working or something.