Hi Donna,
You've probably tried the upgrade with any anti-virus uninstalled or at least disabled, but if not, that can be a problem.
Some USB mice and keyboards can cause failure--I've seen warning about them, but never encountered one.
Another possible reason for failure is a badly corrupted W7 system whose corruption has survived even a W7 repair install. For example, if the W7 can't install all the W7 updates, including optional updates, then it's still corrupted and may not upgrade to W10.
But you may have hit a bios that just won't upgrade, in which case you could check if the manufacturer has a bios upgrade (common with Dell systems, for example).
You may have already mentioned this, but what's the make and model of the computer, along with anything like a service tag?
With Dell systems, for example, you can use the service tag to see if there are any W10 downloads--if not, it may be a system that someone managed to make work with W7, but which isn't supported for W10. I've seen old systems that have been kinda-sorta upgraded to work on W7 and W8, but which had to have their embedded ethernet and video cards disabled and generic ethernet and video cards installed in the expansion slots. Last month I saw a Dell T3500 like that, with unsupported W8 installed and not activated and add-on cards.
The same sort of thing was common with older W98 and XP systems, with lots of fudging to make them work with older and newer Windows versions to suit gamers who wanted to turn newer XP computers into fast W98 systems and offices that wanted to upgrade paid-for W98 systems into XP.
Cheers,
Carl
