I was sending bitcoins from wallet1 to wallet2 on the same machine in Bitcoin-QT.
Open Bitcoin-QT with wallet1. Send the bitcoins. close Bitcoin-QT. mv wallet.dat wallet1.dat.
mv wallet2.dat wallet.dat
I did it several times to make sure it was working, then did a relatively large one.
The large one has not arrived!
When I load wallet1, it says it is confirmed with the bitcoins missing, but the top transaction on the list, the big move to the other one, shows zero confirmations. This transaction does appear to show the right address, which was stored in my address book, and had worked in the tests. But it doesn't make any visible progress.
When I load wallet 2, I see no sign of the incoming bitcoins.
Help! What happened? How do I recover this? I have backups at every stage.
As stated, check the blockchain.info website and see if the transaction shows as confirmed there. If so, then you should be ok.
Next step is to run the wallet with the rescan command line option.