Default [Q] Failed to mount /data (Invalid Argument) Error

While trying to flash back to stock from a custom ROM, I made it to the Samsung splash logo, and got stuck there. Went into recovery and saw the following:

E:failed to mount /data (Invalid Argument)
can't mount '/data' (invalid argument)

[The Applied CSC code is ATT and successfully applied multi-CSC stuff appear in Manual Mode]


E:failed to mount /data (Invalid Argument)
can't mount '/data' (invalid argument)
E:failed to mount /data (Invalid Argument)


Now what must I do to get everything back to the normal? Please help!