Has Glenn Miller's plane ever been found?

Answer 1

There was no real search immediately afterwards. The Battle of the Bulge began the next day* and no one was even aware that the plane was missing for several days. There were simply no available resources to search for it given the magnitude of the conflict.

In the 1980s a wealthy young British businessman financed a search for the plane and claimed to have found some artifacts but nothing was ever proven. A BBC investigation in 2004 determined that all that would probably remain of the small C-64 plane would be the engine block, and that a search would be near-futile because the block would be buried with thousands of years worth of other debris on the bottom of the English Channel.

(*) In fact, the run-up to the Battle of the Bulge may have contributed to the crash. All non-essential air traffic had been halted for that reason as well as bad weather, and bombing sorties were very heavy. The fact that Miller's plane was making an unauthorized flight AND hundreds of returning bombers were dropping unused shells into the Channel before landing was a prescription for tragedy.

Answer 2

In 1985 a wealthy British businessman launched an expedition to try to find the plane. He claimed to have discovered debris but nothing was ever conclusively proven. The C-64 Norseman in which Miller was flying was not a very substantial aircraft, and some later experiments indicated that nearly all of the plane except its engine would probably have been corroded by seawater within a couple of decades so it's extremely unlikely that any evidence will turn up barring an unusual stroke of luck on the part of some future explorers.