Easy

SELECT * FROM gallery2 WHERE topic_id="1785920" UNION SELECT * FROM gallery2 WHERE topic_id="1283453" UNION SELECT * FROM gallery2 WHERE topic_id="1449114" UNION SELECT * FROM gallery2 WHERE topic_id="1383649" UNION SELECT * FROM gallery2 WHERE topic_id="311071" UNION SELECT * FROM gallery2 WHERE topic_id="1517509" UNION SELECT * FROM gallery2 WHERE topic_id="1691087" UNION SELECT * FROM gallery2 WHERE topic_id="1482393" UNION SELECT * FROM gallery2 WHERE topic_id="250284" UNION SELECT * FROM gallery2 WHERE topic_id="410567" UNION SELECT * FROM gallery2 WHERE topic_id="1823757" UNION SELECT * FROM gallery2 WHERE topic_id="959299" UNION SELECT * FROM gallery2 WHERE topic_id="1212495" UNION SELECT * FROM gallery2 WHERE topic_id="1359982" UNION SELECT * FROM gallery2 WHERE topic_id="794116" UNION SELECT * FROM gallery2 WHERE topic_id="1685485"