Before you get you panties in a major bunch, everything IS still on your Hard Drive. You just can't see it.
When you delete something it doesn't get rid of it, just marks it. Kinda like taking the garbage bag w/garbage out of the can and put it by the door to take out. The garbage IS still there until you throw it out.
What to do, there are recovery programs you can use to go out and recover what you lost. They run about $40 to $60. One note, other than the recovery program, DO NOT ADD OR DELETE ANYTHING FROM YOUR HARD DRIVE. Load the recovery program and recover what you lost, then save as much of it to a USB or another HD.
If you lost 10 years of data, then every Windows update won't be there, which of course will require 9 billion downloads with the required 9 billion restarts. That will be about as fun as being pinned under a car trying to reach for a jack that is just out of reach.