You might be came from youtube.

so here's the file.

If you don't 
please follow the procedure given below....


After downloading , extract the keygen file

- open cmd


-drag the ’” Mathematica_10.4.0_Keygen.exe” to cmd
-Hit enter
-now paste here your math id and hit enter.

-Here you’ll have your Activation key and Password.
-Copy it .

-You are all set.


Regards

XT