Android : android : my android java code not readable try to reopen this

i am working with Android studio 1.1.0 . i closing my android project today . and after 1 hour reopen this but 2 my java class of 6 class is not readable and filled by (null) . the size of this file is correct (21 KB) and (17 Kb) , but not readable ... try to opening by notepad++ but this software cannot read my project code is lot and take write 2 week please help me to recover my code. tnx