According to the Wikipedia SR-71 page, 12 of the 32 planes were destroyed in accidents. The page if full of info on the history of the planes: http://en.wikipedia.org/wiki/Sr-71 Below is the list showing the fate and disposition of the 32 planes.
List of SR-71 Blackbirds
Serial number / Model / Location or fate
61-7950 SR-71A Lost, 10 January 1967
61-7951 SR-71A Pima Air & Space Museum, Tucson, Arizona
61-7952 SR-71A Lost, 25 January 1966
61-7953 SR-71A Lost, 18 December 1969
61-7954 SR-71A Lost, 11 April 1969
61-7955 SR-71A Air Force Flight Test Center Museum, Edwards Air Force Base, California[74]
61-7956 SR-71B Kalamazoo Aviation History Museum, Kalamazoo, Michigan
61-7957 SR-71B Lost, 11 January 1968
61-7958 SR-71A Museum of Aviation, Warner Robins, Georgia
61-7959 SR-71A Air Force Armament Museum, Eglin Air Force Base, Florida[75]
61-7960 SR-71A Castle Air Museum, Atwater, California
61-7961 SR-71A Kansas Cosmosphere and Space Center, Hutchinson, Kansas
61-7962 SR-71A American Air Museum in Britain, Imperial War Museum Duxford, Cambridgeshire, England[76]
61-7963 SR-71A Beale Air Force Base, Marysville, California
61-7964 SR-71A Strategic Air and Space Museum, Ashland, Nebraska
61-7965 SR-71A Lost, 25 October 1967
61-7966 SR-71A Lost, 13 April 1965
61-7967 SR-71A Barksdale Air Force Base, Bossier City, Louisiana
61-7968 SR-71A Virginia Aviation Museum, Richmond, Virginia
61-7969 SR-71A Lost, 10 May 1970
61-7970 SR-71A Lost, 17 June 1970
61-7971 SR-71A Evergreen Aviation Museum, McMinnville, Oregon
61-7972 SR-71A Steven F. Udvar-Hazy Center, Washington Dulles International Airport, Chantilly, Virginia
61-7973 SR-71A Blackbird Airpark, Palmdale, California
61-7974 SR-71A Lost, 21 April 1989
61-7975 SR-71A March Field Air Museum, Riverside, California[77]
61-7976 SR-71A National Museum of the United States Air Force, Wright-Patterson Air Force Base, Dayton, Ohio
61-7977 SR-71A Lost, 10 October 1968
61-7978 SR-71A Lost, 20 July 1972[3]
61-7979 SR-71A Lackland Air Force Base, San Antonio, Texas
61-7980 SR-71A Dryden Flight Research Center, Edwards Air Force Base, California
61-7981 SR-71C Hill Air Force Base Museum, Ogden, Utah