Several possibilities occur to me, but some additional information would be helpful in narrowing down the possibilities.
  1. Had you been able to successfully read the note previously?
  2. Before attempting the Time Machine Restore, were the cards readable?
  3. Are any of the Contacts entries readable since the attempted Time Machine restore?
  4. Describe the process you used in restoring from Time Machine.
  5. Specifically what file did you restore from Time Machine?
  6. How did you choose the date you restored from?

If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein