When I get to the beach I see the body, there is no siren to fight it .. When I examine the body, Garret bends and says nothing ... There is no possibility to do "Loot" to her body, nothing! I am using version 1.31
What can I do? Thanks!

Have any mods installed? Did you try repair/verify the game?

Did you use Keira's magic lamp? And who is Garret?

MaxStrauss is correct, you need to use Keira's magic lamp on (or near) the body, listen to the brothers and then follow the footsteps.

I tried to use the lamp ... Even before you have to use the lamp, I try to press "exmaine" on the body and nothing happens. Geralt bends does not mean anything ... Quest is not updated, and does not tell me to use the lamp

Whenever you encounter a character or object that you are supposed to interact with and cannot, save the game and reload. It sometimes happens in games where objects become bugged and can't be interacted with. Saving and reloading usually fixes things. If that doesn't work, then remove any and all mods you have and verify/repair your installation.

I have no moods on the game. I saved and loaded the game a few times, it did not help ... I will try to fix the files .. By the way, I play also on the laptop, and also put the exact same problem .. Save a game of synchronizing, to the cloud of gog

Then if verifying/repairing your installation doesn't help, it means your saved game is corrupt.