How do i get rid of this virus on my computer?

ok my cpu is def infected with something i like cant do anything without this message offer coming up that says win 7 antispyware 2012 has blocked a program from assessing internet and says internet explorar is infected with trojan bnk. win32.keylogger .gen priv data can be stolen by third parties and has u selwct either yes to activate win spyware or no continue unprptected ... no doesnt work snyway and if yes u have to buy it which costs 70 bucs for a yr... idk if its a fake thing or what but i cant use internet at all cause this whatever wont let me and i dont even own this program idk if its part of the virus or what i cant download any anti virus cuz it wonyt let me onlune and even my cpu dont let me without me runnin into this thing ..it has to be part of the virus idk what to do please anyone what do i do how do i stop this?