Simple

SELECT * FROM gallery2 WHERE topic_id="758425" UNION SELECT * FROM gallery2 WHERE topic_id="762135" UNION SELECT * FROM gallery2 WHERE topic_id="1690608" UNION SELECT * FROM gallery2 WHERE topic_id="412689" UNION SELECT * FROM gallery2 WHERE topic_id="1622016" UNION SELECT * FROM gallery2 WHERE topic_id="1132039" UNION SELECT * FROM gallery2 WHERE topic_id="23970" UNION SELECT * FROM gallery2 WHERE topic_id="680530" UNION SELECT * FROM gallery2 WHERE topic_id="403636" UNION SELECT * FROM gallery2 WHERE topic_id="1243112" UNION SELECT * FROM gallery2 WHERE topic_id="1802055" UNION SELECT * FROM gallery2 WHERE topic_id="1718817" UNION SELECT * FROM gallery2 WHERE topic_id="355896" UNION SELECT * FROM gallery2 WHERE topic_id="909586" UNION SELECT * FROM gallery2 WHERE topic_id="1549062" UNION SELECT * FROM gallery2 WHERE topic_id="218117"