No, i did not safed the bak file before, i did not expect that the system will remove the renamed wallet.dat
and yes, i know the adress, i have a backup of the old wallet.
It was, the system saw my renamed file from bak to dat and then then instead of using it, or giving another error, it created a new wallet.dat file
but before it created it, it deleted or moved it, i can not see any reason why this program will remove it to nowhere, i guess and hope its safed somewhere.