I read quite a lot 6600 owner have same problem.
and I did searched through whole drive from c, d, e and z drives using FExplorer even open each folders. PLus tried on File Manager too.
And I still cant find mmcStore file which I read can be reset my password.
ps: I remember I didnt set any protection password for my MMC but it prompt to enter password after I fully format my 6600 by using green, No. 3 and * buttons.