From the Mouse himself:
Q: I purchased theme park tickets years ago and never used them. Are they still valid?
A: Walt Disney World Resort continues to honor all unexpired theme park tickets with remaining admission days.
The FAQ goes on to discuss the No Expiration Option that Disney once offered.
However, be aware that unless you purchased the No Expiration Option, theme park tickets purchased after 2004 expire 14 days after their first use. While the No Expiration Option is no longer available, if you have previously purchased theme park tickets with the No Expiration Option, your tickets will still be honored. https://disneyworld.disney.go.com/faq/tickets/converting-old-tickets/
What is not abundantly apparent in Disney's carefully worded policy, is that Disney has TWO policies on unused tickets. One for completely unused tickets (will honor these), and another for partially used tickets (will honor these if purchased with the No Expiration Option).
The OP's predicament concerns his completely unused park tickets. For questions on specific tickets, he can also call 407/939-1289.
For a discussion on partially-used tickets, see the thread "Partially Used Tickets vs No Expiration Option".