You should have a recovery partition on your system. You can get to it by tapping F8 during boot up. Please note that in Windows 10 Microsoft has been the boot process a lot faster which makes it harder to get to the recovery menu so don't be surprised if it takes a few reboots to get to the menu. It's even harder to get to it if you have a SSD drive. If you have an install disc or usb you can also repair from that.
I suggest that once you have everything up and running you make a system image file.
I use EaseUS Todo backup and recovery.
It will make a boot disk that will boot your computer and recover it (from a backup file on your computer) to the way it was when you made the back up.
If you only have one hard drive you will need to create a partition on it, (using Disk Management) to save them to.
They can't be on the partition you are restoring.
I make a new backup once a month, it takes about 20 minutes.
It has saved me from a lot of pain on several occasions since I started beta testing Windows 10, and just the security of knowing that I can have everything back up and running in a half hour is worth the effort.