基本上算是正确表达.
如果要求完美,可以加一个词,变为下面形式就更好：
Where are the tickets?I can not find them 【anywhere】.
正确形式是
Where are the tickets?I can not find 【their代词所有格,作定语——them 宾格,作宾语】
祝你开心如意!是不是Where are the tickets?I can not find their 不对？是的。看看上面解释。