The problem starts here, i read that the preferneces file of logic : com.apple.logic.cs and .plist should be present in : myHD/library/prefernces/
There i find all my .cs and .plist file, but not the logic one!
You are looking in the wrong "Library".
Logic preferences are saved in the <User> Library:
Note that the User Library is hidden by default in Lion and M Lion. One easy way to get there is to use the Finder:Go menu whilst holding down Option (the User Library will appear in the menu).