[Axapta-Knowledge-Village] Urgent Help, class I created lost after reopening axapta

[XeN]

I use axapta 3.0 sp5 with full updates and kernel rollups. Yesterday I 
created a new class, axapta named it Class2 by default and I changed it 
in class declaration, added many methods on it, and succesfully saved 
and compiled it, after I reopened axapta I saw the class name on 
project window but when I clicked on it, it became "Class2" again when 
open it, saw all the code and methods lost! How can I bring it back?