Try the following in the qt client in Help -> Debug window -> Console:


with the TXID being the transaction ID of the transaction which didn't went through (according to your post, "2c6211006e683f5efc63f4f77e46ee96c68b0ac34e0479831ad5a8f069a2222c").

If your coins still are not back, try:


Don't worry about the red warning in the window, these commands do nothing that allows me to steal your coins Rescanblockchain only updates your wallet database (without touching your keys) so the unconfirmed transaction is deleted.

Or on the command line:


Make sure your client is updated to a reasonably new version (0.9+). If it's older it may be the case that the transaction format is wrong. In this case, backup your wallet.dat and download 0.9 or the brand new 0.10.