Android : Android studio's file explorer has changed

(sorry for my bad English)

I just opened android studio and i noticed that the project explorer ( hierarchy viewer ) has changed and the project doesn't compile any more because the files are not in their proper location. here's what the project viewer should be :

and now it's like this

i can notice also that ANDROID logo has disappeared from the viewer :

and i also get this error message

please help me :(