Like others, since you have not had any activity for over 2.5 years ( or more -- might help if you can fill in the activity history), you are not likely to get a positive response from UA While others have been successful in restoring miles, by a challenge or finding an old uncredited item, being more than 12 months after expiration is more than others have reported.
some related threads that may help
http://www.flyertalk.com/forum/unite...ad-merged.html
http://www.flyerguide.com/wiki/index...Expiration_(UA)
http://www.flyertalk.com/forum/unite...d-threads.html
http://www.flyertalk.com/forum/unite...red-miles.html
http://www.flyertalk.com/forum/unite...6-wks-ago.html