[shock]

Oh, well you're gonna struggle a lot with that, I've tried it before and it's almost impossible.

What I would recommend though, is either to hack the admin's email and just do a password reset, or to impersonate the admin if there is more than one staff, like for example there are 2 owners, you send an email like to one saying "hey, forgot the wp admin password, please send it to me on randomuser@Gmail.com, as my password reset isn't working because my email doesn't want to receive emails" or something like that. It's rather easy to hack websites, not because the cms is weak (wordpress is rather strong with passwords), but because admins are usually rather stupid.

Hope this helped!