WINDOWS 8.1 corrupted, hao-hao-cai2014-10-02 18:38:44

I want to re-install, it asked product key, I give the PC INFO listed PRODUCT ID, it denied.
 By the way,  it is a lenovo windows 8.0, I updated it into 8.1
 I lost the original product key (CD/DVD etc).
 
The problem is caused by my installing AVG(anti virus software) ? Right now, the control panel cannot be open.
Chrome is still ok, FireFox is down also.

Do you have any good suggestion?

可以backup CD key出来或者启动时候按F8进入修理菜单

or use lenovo one key recovery

谢了！