Everything in %year% is gone. I'm not sure why.. I just upgraded Traktor 3.4 to Traktor Pro, which might have something to do with it. I hope there is a way to recover this.
All my albums are in their own folders and I'm hoping I can get the Year field back from the folder name. All the folders are named as followed:
"%artist% - %album% (%year%)"
Pretty simple. Is there a way to retrieve the %year% from the folder name?
Sure thing. Mark all you need to restore, click »Filename -> Tag« and enter something on the lines of:
%dummy% - %dummy% (%year%)\%dummy%
(This would be valid if you run on some Windows box using \ as folder separators. The %dummy%s will automagically be thrown into the bit bucket.)
Watch for the display (while you type, it shows what it will »interpret« just below the input field) and when everything is well just give your »OK«.
(If you want to be 100% sure, you can also click on »Preview« before making the actual changes.)
Perfect! Thank you so much!!! 
Thank Florian, other people that gave input, and Mp3tag 