I have installed AUCTEX from inside emacs (i.e. M-x list-packages) and according to preview-latex manual, the installation of it is already included when installing AUCTEX. But when I tried to load AUCTEX and preview-latex by adding the following lines:
(load "auctex.el" nil t t)
(load "preview-latex.el" nil t t)
into my init.el file, it cannot load preview latex saying that.
File is missing: Cannot open load file, No such file or directory, preview-latex.el
Moreover, quoting AUCTEX manual
You can detect the successful activation of AUCTEX and preview-latex in the menus after loading a LaTEX file likepreview/circ.tex: AUCTEX then gives you a ‘Command’ menu, and preview-latex gives you a ‘Preview’ menu.
but where do I find these 'menus'?
EDIT: Another part of the manual says that
With Emacs (or if you explicitly disabled use of the package system), the startup files auctex.el and preview-latex.el may already be in a directory of the site-start.d/ variety if your Emacs installation provides it.
The file auctex.el is in the .emacs.d/elpa/auctex-12.1.1/ where I expect to find preview-latex.el but I don't. There do exist preview-latex.info and preview-latex.spec in that directory but the file preview-latex.el is found in another path .emacs.d/elpa/auctex-12.1.1/tests/japanese/ (I bought my laptop in Japan in case that matters).
I am using GNU Emacs 26.