Using an online guide that walked me through it, I killed Finder through terminal commands. Now I’d actually like to have it back, but I have no idea what I need to do. How can I restore Finder in OS X?
Time Machine would only help you in the future. Is your Mac set up with Time Machine? If so you should be able to get the deleted files that way. Click the Time Machine icon in the dock. Then go back to before you deleted the files, they are probably still available.
If you don't have a Time Machine backup yet,
Maybe you can try uFlysoft Data Recovery for Mac, it can recover empty trash on Mac only in three steps:
Step 1. Launch the software to scan the device where your files deleted
Step 2: Preview the scan result files and make mark if it is the one you find
Step 3: Recover files