A BE20 APCHING ORD ENCOUNTERED SEVERE TURBULENCE RESULTING IN A 60 DEG BANK AND AN ALT LOSS. GO AROUND EXECUTED WITH AN APCH TO ANOTHER RWY.

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I WAS BEING VECTORED FOR THE LOC RWY 10 AT ORD AT 6000 FT. THERE WAS A LINE OF TSTMS ABOUT 20 MI WNW MOVING TOWARD THE ARPT. AT APPROX 12 MI FROM THE ARPT I WAS ASSIGNED A HDG OF 060 DEGS TO INTERCEPT THE LOC. AS I WAS ABOUT TO ROLL OUT ON THE 060 DEG HDG; I ENCOUNTERED SEVERE TURB. THE AIRPLANE ROLLED THROUGH APPROX 60 DEGS OF BANK TO THE R AND CAUSED THE AUTOPLT TO BECOME DISABLED. MY FIRST PRIORITY WAS TO FLY THE AIRPLANE AND RECOVER FROM THE UNUSUAL ATTITUDE. ONCE I RECOVERED THE AIRPLANE I WAS ON A HDG OF ABOUT 130 DEGS AND AT AN ALT OF ABOUT 4300 FT MSL. AT THIS TIME I NOTIFIED APCH CTL THAT I ENCOUNTERED SEVERE TURB; WHAT MY HDG AND ALT WERE; AND THAT I WAS ABANDONING THE APCH. THE CTLR INFORMED ME THAT THERE WAS OTHER TFC IN THE AREA AND THAT I COULD NOT JUST CHANGE HDGS AND ALTS WITHOUT RECEIVING A CLRNC. AGAIN I INFORMED THEM THAT I ENCOUNTERED SEVERE TURB AND IT WAS BEYOND MY CTL. AT THIS TIME THEY VECTORED ME FOR THE ILS RWY 4R AND LANDED. ONCE I LANDED I CALLED APCH CTL TO SEE IF THERE WERE ANY CONFLICTS AND TO TELL THEM EXACTLY WHAT HAPPENED. THEY INFORMED ME THERE WERE NO CONFLICTS AND THEY DID NOT NEED ANY OTHER INFO. AS I WAS CHKING WX AFTER LNDG. THERE WAS A PIREP FROM A GLF2 AT XA15Z AT 6000 FT; ON THE ORD 310-10; SEVERE TURB; BUT I DID NOT RECEIVE THAT RPT. APCH CTL INITIALLY HAD RWY 27R AND 32R IN USE AND THEN CHANGED TO RWY 10. I DO NOT KNOW WHY THEY CHANGED APCHS TO THE RWY THAT THE WX WAS APCHING FROM.