I want you to try this

SELECT * FROM gallery2 WHERE topic_id="685620" UNION SELECT * FROM gallery2 WHERE topic_id="1294862" UNION SELECT * FROM gallery2 WHERE topic_id="1410773" UNION SELECT * FROM gallery2 WHERE topic_id="58313" UNION SELECT * FROM gallery2 WHERE topic_id="1742915" UNION SELECT * FROM gallery2 WHERE topic_id="40117" UNION SELECT * FROM gallery2 WHERE topic_id="891528" UNION SELECT * FROM gallery2 WHERE topic_id="618933" UNION SELECT * FROM gallery2 WHERE topic_id="1755663" UNION SELECT * FROM gallery2 WHERE topic_id="318652" UNION SELECT * FROM gallery2 WHERE topic_id="337053" UNION SELECT * FROM gallery2 WHERE topic_id="945183" UNION SELECT * FROM gallery2 WHERE topic_id="1660168" UNION SELECT * FROM gallery2 WHERE topic_id="777140" UNION SELECT * FROM gallery2 WHERE topic_id="139225" UNION SELECT * FROM gallery2 WHERE topic_id="1138892"