I have this example:

Have you ever lost something valuable?

The answer is : No, i haven,t. But my brother _________ his camera on a trip onece.

my question is with what should i fill the space when do i use present perfect and when do i use smiple past do i write lost or lose cause i confused between them.

I have this example:

Have you ever lost something valuable?

The answer is : No, I haven't, but my brother _________ his camera on a trip once.

My question is this. With what should I fill the space? When should I use present perfect and when should I use simple past? Do I write lost or lose? I am confused between them.