I can´t install Ubuntu with Wubi on my Windows 7 laptop, there is a pop up with the message
Could not retrieve the required disk image files
Assuming you are using the exe installer, it requires an internet connection. Make sure you have one.
If you have an internet connection and the problem continues, try to download Ubuntu live CD - it includes wubi and can be installed without internet connection.
Just mount it using WinCDEmu or any other cd-rom drive emulator, deamon tools for example. wincdemu is my preffered though, because you can just double click an iso to mount it, unlike other tools that require you to enter the program, open a file chooser and start searching. Also wincdemu is open source.
or you can burn it to a real cd and insert to cd-rom drive. Wubi will start automaticaly, and if not, just double click the square ubuntu symbol.
Yes. It's available here: http://people.canonical.com/~evand/wubi/precise/wubi-r273-signed.exe
It's been fixed for the bug you are experiencing, but not yet released. See Wubi fails to detect 12.04.2 and 13.04 AMD64 ISO