Q: BOOTCAMP

Just a guess but formatting the Windows partition is what probably caused the problem. I think you may have to remove the Windows partition using Boot Camp Assistant, then start over.

Is you ISO a mixed 32-bit/64-bit ISO?

What is the size of the ISO file? Can you open autorun.inf in a text editor and post the contents?

This looks like a mixed 32-bit/64-bit installer. Can you download the 64-bit only ISO from https://www.microsoft.com/en-us/software-download/windows7 using your W7 Product Key?

You can install W7 64-bit using an ISO from Microsoft or from your copy.

Please see Install Windows 7 and earlier on your Mac using Boot Camp - Apple Support and ensure pay attention to steps (especially step 11) under section titled Perform a new install of Windows 7 .

Is that the only content? Do you see any references to the number 64? This does look like mixed installer.

On my 64-bit DVD, I have these

[AutoRun.Amd64]

open=setup.exe

icon=setup.exe,0

 

 

[AutoRun]

open=sources\sperr32.exe x64

icon=sources\sperr32.exe,0

For a 32-bit DVD (or mixed DVD), I have...

[Autorun]

open=setup.exe

icon=setup.exe,0