I have a Toshiba Satellite L455D-S5976 that had Win7 Premium installed. I did a “refresh” on the machine, and installed Win10. Then I left it alone for several weeks, went to start it and it wouldn’t recognize password or Identification answers.
I have used Ubuntu in the past but the only DVD I have is a Mac version. Can I download Ubuntu and copy it to a DVD? Bios will allow boot from DVD or HDD but not from a thumb drive. Any version?
A DVD is a DVD is a DVD; all have the same formatting, whether created on/for a Mac, Windows PC, or Linux PC. What's on that DVD may be an Ubuntu installer that's fresh, or stale, but it's equally readable on all major operating systems.
The currently supported versions of Ubuntu and its flavours are 16.04 LTS, 18.04 LTS, and 19.10.
Your Toshiba has an old AMD Sempron SI-42 (2.1 GHz) CPU and SATA-I (not SATA-III) drives, so with the standard 2 GB of DDR2 RAM, ATI Radeon 3100 GPU, and 802.11 b/g WiFi, you might find the standard Ubuntu 18.04 with its demanding GNOME3 Desktop Environment kinda poky.
Instead, https://ubuntu.com/download/flavours shows versions with different Desktop Environments which are less demanding (except for special distributions like Studio and Kylin). I'd suggest you consider one of those instead.
Once downloaded, that ISO file you use to create a LiveDVD should be checked for download errors by https://tutorials.ubuntu.com/tutorial/tutorial-how-to-verify-ubuntu#0 .
Once verified, you can create a LiveDVD for testing and installation using Ubuntu, Windows, or MacOS X.
