Hello Barbara W,
The fact that the keyboard works ok in the BIOS but not in Windows suggests one of two things as being the cause, the USB ports are disabled in the BIOS or there is a driver issue within Windows.
What I would suggest: 1. make sure that your keyboard is connected to the rear USB port 1 as shown in the attachment below, this because on many Dell computers the USB port 1 is enabled by default, if this does not help go to the second suggestion. 2: restart the computer to access the BIOS, look for an option such as restore default factory settings or load fail safe default settings, when you find it, select the option then press F10 to save and exit then test.
As an asides, can I ask why you needed to update the BIOS, were you already having problems, reason that I ask is because updating the BIOS should only be done to fix a known issue or to allow for an upgrade such as a better processor that requires a newer BIOS, the potential for a BIOS update to go wrong and ruin the motherboard altogether when there will be no actual benefit from doing so is just not worth the risk.
NB: Just a bit of a rant on my behalf but I so dislike motherboards that do not have PS/2 type keyboard and mouse ports, if by chance you cannot get the USB ports working on a board such as yours they are totally unusable and have to be tossed in the trash
I tried my recovery usb stick and it appeared to be running but after 6 hours I stopped it. I restarted using the recovery and chose the option to recover using the hard drive and it appeared to be running, but did not finish after a similar length of time.
What version of Windows is on the recovery USB stick, if not mistaken your computer shipped with Windows 7 and has been upgraded to Windows 10, any recovery partition on the HDD will be the original OS such as Windows 7 and not Windows 10.