Error ORA-00054 resource busy and acquire with NOWAIT specified or timeout expired in oracle11g

Try to execute this first ,and check whether anyone from other session or your session put a lock on that table .If you have put a lock on that table,try to do commit/rollback .If someone else put a lock ,ask him/her or if you have rights kill his session .And then drop the table.

           select session_id "sid",SERIAL#  "Serial",
    substr(object_name,1,20) "Object",
      substr(os_user_name,1,10) "Terminal",
      substr(oracle_username,1,10) "Locker",
      nvl(lockwait,'active') "Wait",
      decode(locked_mode,
        2, 'row share',
        3, 'row exclusive',
        4, 'share',
        5, 'share row exclusive',
        6, 'exclusive',  'unknown') "Lockmode",
      OBJECT_TYPE "Type"
    FROM
      SYS.V_$LOCKED_OBJECT A,
      SYS.ALL_OBJECTS B,
      SYS.V_$SESSION c
    WHERE
      A.OBJECT_ID = B.OBJECT_ID AND
      C.SID = A.SESSION_ID
    ORDER BY 1 ASC, 5 Desc