Simply speaking, they are still there.
When you delete a file, it still stays where it was before. You are deleting only its directory entry (the complete path and filename of the file).
When the above operation is completed, your Operating System (Windows) sees that space as an empty space, which allows to overwrite that space with a new data (file/files).
That's why, after deleting a file, and before writing anything else into its space, old file is fully recoverable.
Same goes for Recycle Bin operation.
When you delete a file, file doesn't move to Recycle Bin. Only file's its directory entry goes there. That's why you can easily move a file back, and forth from Recycle Bin.
