Finally , I had to replace the sensor aswell as use the tapetrick. The one that worked for me was the one with scoth tape and a marker. tried all the other stuff here, but the tape stuff worked, and finally this is not a software issue, i tried the mainboard in an other phone , an the the proxi sensor and rest worked fine , and swapped back again, then it was just as bad. So that proves its not a software issue. Softwaregeeks ! Why i had to change the sensor was probably caused by the cracked screen. Took me all together at least 3 hrs. 2 different screens and a new prxsensor. (and some scoth tape.)