Hi, I'm Ashik. Welcome to JustAnswer. I'm reviewing your question now, and will post back with your reply ASAP
If the windows are frozen, then you can force quit them. Press Command, Option and Esc keys and this will bring Force quit window (or click on Apple icon and select Force Quit). Select the frozen window/application and click Force quit. Click Finder and select Relaunch in there.
The scanned documents should be normally saved in Documents or Pictures folder. Click on the Finer icon on the dock. Then in Finder, click on Go menu at the top bar and select Home. This will open your home folder. You can find the scanned documents in Documents or Pictures folder unless you moved to different location. Check all the folders inside your home folder for the folder.
If you don't see them, then just search them on Spotlight (magnifier icon at top right of the screen). Just enter the folder or file name there and it will show them.
Please let me know if that didn't work, so I will continue to help you