From Wikipedia:
In 1930 Republican Charles F. Curry, Jr. was elected to the House as a write-in from Sacramento, California. His father, Congressman Charles Curry Sr., was to appear on the ballot, but due to his untimely death his name was removed and no candidate's name appeared on the ballot.
Democrat Dale Alford was elected as a write-in candidate to the United States House of Representatives in Arkansas in 1958.
Republican Joe Skeen was elected as a write-in candidate to Congress in New Mexico in 1980.
Independent Ron Packard was elected to the House in California in 1982 and was the only write-in candidate to defeat the candidates of the Democratic and Republican parties. He immediately aligned himself with the Republican party after the election.
Democrat Charlie Wilson, the intended Democratic candidate for the 6th Congressional District in Ohio, did not qualify for the ballot because only 46 of the 96 signatures on his candidacy petition were deemed valid. The Democratic Party continued to support Wilson, and an expensive primary campaign ensued. Over $1 million was spent by both parties. Wilson overwhelmingly won the Democratic primary as a write-in candidate on May 2, 2006 against two Democratic candidates whose names were on the ballot.
Let me add one more: DC Mayor Anthony Williams was re-elected in a write-in campaign.
Of course, write-in victories are rare, but that's partly because serious write-in candidates are rare.
That's an impressive compilation but I continue to believe a write-in campaign would be an uphill battle.
I am more hopeful that the AP story is wrong, in whole or in part.