SE P990i phone lock for master reset ?

my p990i is unlocked and working but it's lock code is unknown so cannot master reset. i've read many forums used codes suggested but it says wrong code.

i've phone xs v2, but when i connect my phone to usb holding ( c key ) my pc detects phone first and phone xs cannot.

i've flashed my k750, changed icons etc. but this problem dosent happens with k750 that pc detects before phone xs.

please suggest me how can i know my phones code as i am sure it is change by someone.

Thanks.