The WUBI installer is on the 14.04 ISO and works with windows up to 7. Windows 8 and Windows ME are not supported by WUBI. The only ISO that does not have WUBI is the 13.04 version (and that is end of life already)
Take note of the accepted upvote on the 1st link from a developer of WUBI. Copied parts from META:
It has shipped on the CD and is still shipped. Primary function is to
be a "cd autolauncher" for people who pop the cd into a Windows
machine, at that time it says "You need to reboot, to try ubuntu!
[reboot now]" or some such.
If one copies the wubi.exe off the cd, it will launch and offer Wubi
If one downloads wubi.exe off official release mirrors or
releases.ubuntu.com, it also works.
It works O.K. for all defined flavours i386/amd64 builds in BIOS mode.
There is no confirmation if it works with UEFI, UEFI Windows 8, UEFI
Windows 8 + SecureBoot. The last one believed to be the typical
configurations of new computers that do not come with ubuntu
Since it's no longer an optimal solution for the default new installs, it has been de-emphasised on the ubuntu.com/download website.
Officially it is still supported - precise has 3 more years of support, and wubi has not yet been removed from any isos and is present to download for all releases and is present on all released .isos. (12.10, 13.04, 13.10 and 12.04.x point releases)
Mind the operating system noted not including 14.04 because this was posted before the release of 14.04. Support for WUBI has NOT dropped; it is no longer the preferred method though since Windows 8 does not play nice but if you have Windows 7 or older (excluding Windows ME) all you need to do is copy the installer from the ISO and it will install.