when i delete an icon or a picture, it goes to trash. how do i get it back from trash?
in this case its most likely gone. There is one place you can look. There is folder on the sdcard called .trash-1000 it is a hidden folder so you would need to look at the sd from a computer make sure you are able to see hidden folders and look in that folder thats on the root of the sdcard.
If its not there you would need to either get some drive recovery software or pay a data recovery company to retrieve the image and even thats not guaranteed. But what is guaranteed is either option is not cheap.
depending on what operating system you are using the steps to be able to view hidden folders will be different.