The problem is that Microsoft broke the Digital Distribution of Windows 7 and replaced it with the non-functional Microsoft Software Recovery Tool. There is no means of downloading a .iso for the Dell Windows 7 OEM license. If you have working factory settings you can create Recovery Media using Dell Backup and Recovery as demonstrated here: [URL] Factory settings aren't equivalent to a clean install but when Windows 10 is out in late summer (which is a free upgrade for Windows 7 users) a .iso should be provided for clean installation. [IMAGE] Otherwise as you are in the US. If your system is in warranty you may procure installation media from Dell going to: www.dell.com/recoverymedia  Unfortunately most Windows 7 systems will have expired warranty and Dell are making it difficult to procure installation media simply because of Microsoft's policies.
I have been searching for a link to download the windows 7 iso to create an installation disk. I have not been successful so far. Inspiron 660
Windows 7 installation disk