>>f I wanted to return to using windows 10, as I don't like the formatting in win 11- specifically the drop down menu changes, without a licence key (can't find my disk) would it be free and possible ?
You can as long as the OEM provides support for Windows 10 and allow a free downgrade. Some OEMs provide, and some do not. Disk cannot be found because it will require disabling VND option in BIOS.
If the context menu is the only problem, please see:
https://answers.microsoft.com/en-us/windows/for...
This will restore old right click context menu of Windows 10.
Hope this helps.