I can't restore my iPhone 6?

I had my phone fixed from somewhere and they had taken the Touch ID out, and since then I haven't been able to update my iPhone. The software I have now is iOS 9.1 and it needs to update to iOS 9.1.2
I need to restore my phone because I have no space on it regardless of how much data i delete, however it says that it will restore my iphone when the software has downloaded. I've been waiting for the software to download for about 20 minutes now and it hasn't done anything. How do I restore my iPhone without updating it because I really need to restore it.

You need to hook it to your computer. It needs to be done on iTunes on your
computer.