how to reset vim's settings (including plugins

Question

I have been using vim for two years, and I use "pathogen" for plugins manage. I am seeking a way to reset all vim's settings (including plugins, .vimrc file) without close vim. Is there any idea?

PS: In some cases, reload vimrc doesnot work exactly the same as reopen vim, so I want to reload the whole state exactly like reopen vim.

Answer 1

From :h set

:se[t] all&             Set all options, except terminal options, to their
                            default value.  The values of 'term', 'lines' and
                            'columns' are not changed. {not in Vi}

Answer 2

It is not clear why would you avoid restarting Vim.

If the problem is to lose the current state of tabpages, windows and buffers it would be preferable to create a session to save what matters and the reload everything else.

Building on Peter Rincker suggestion on the comments, there is a great plugin called session.vim, which makes managing sessions very easy. It also creates the Restart command:

This command saves your current editing session, restarts Vim and restores your editing session. This can come in handy when you’re debugging Vim scripts which can’t be easily/safely reloaded using a more lightweight approach.

The :Restart command worked very well here, so I've never tested the other plugin for the "lightweight approach". But you could try it if completely restarting Vim is not an option.