jph160,

If you have no internet on the E5480 you can take a usb key to another computer and download the drivers from the link below. Bring them back to your system and install them. The chipset drivers are what enable the USB ports to work. There is a Driver Install Order. Click the links below.

Dell E5480 Drivers, Downloads and Manuals

Drivers FAQ

Drivers Install Order

no drivers for Ethernet or wireless showing.

used a dell windows 7 professional disc and added usb 3.0 drivers to allow install.

machine came with windows 10 but we need to downgrade.

many thanks for the reply

problem is there are only usb 3/0 ports on this machine and none are working so cant read any usb keys

are there any other options ?

You need a different model system (an older CPU, ending with the 6th generation  Skylake line).  Anything newer is Windows 10 only - no legacy Windows support.

http://www.dell.com/support/article/us/en/04/sln304217/microsoft-windows-operating-system-support-for-intel-kaby-lake-processors

https://support.microsoft.com/en-us/help/4012982/the-processor-is-not-supported-together-with-the-windows-version-that

The system has a 7th Generation Intel Processor. Windows 7 is only supported on systems with a 6th Generation Intel Processor, no drivers are created for newer models:

https://www.dell.com/support/article/ed/en/edbsdt1/sln304217/microsoft-windows-operating-system-support-for-intel-kaby-lake-processors?lang=en