Dell Optiplex doesn't recognize CD/DVD or USB drives

Hello.  I have a 2012 Dell Optiplex with Win 7 Ultimate loaded at time of purchase.  About 6 weeks ago I upgraded to Win 10 Pro x64 by download and install from the Microsoft site.  All was fine until this morning.  For reasons I can't determine the system isn't accepting my password to logon.  I've tried every password I can think of but nothing works.

I would like to try re-installing Win 10 but getting jammed at the boot up process.  The system doesn't recognize the bootable Win 10 ISO file I got from Microsoft.  I tried it on a DVD and a thumb drive, but neither worked.  I can get into the BIOS settings but no matter how I prioritize the sequence of boot sources it still doesn't work

Is there something I'm missing?  Thanks.