Windows Update is pretty FUBAR on Windows 7/8/8.1 lately, so chances are it's that causing the problems you seem to have with upgrading.
Unless you have some seriously ancient hardware in your setup that simply cannot function in W10, there's no feasible reason why it wont actually work.
As long as you have a legitimate licence for your current OS, you can make a bootable Windows 10 DVD/USB stick with tools that Microsoft themselves supply, and simply input the product key for your current OS when the installer asks you for one.
Edit;
Just now realised you might have meant you're running W10 and it's having problems, it's not entirely clear from your post though.
If that's the case, it's possible something went wrong or got corrupted during the install, an OS refresh might solve it.