finally, I work through. It was so difficult to me. And I am here to tell you what I did. Those are all for wiindows7x64.
1, thanks T.Prince(Quote#2), the msicuu2 is very usefull to unintall. So if you get the crack I sufferd, try the msicuu2.
2. when re-installed MKL 2015, I got another problem. It said "can not open the key.......". try following steps.
1,press "windows" button, select "run", run "cmd"
2.run command secedit /configure /cfg %windir%\inf\defltbase.inf /db defltbase.sdb /verbose
3, reboot windows over, re-install MKL 2015 again. all will be ok.