This thread should be moved to technical support. The option is at the bottom of the page.
From the debug console in the core client (or using bitcoind) you can try:
getrawtransaction 76a4640cf4049e81d228f3a3429159ea35c82202dae6c7648b7f091e8b4fb716
then:
sendrawtransaction <the long hexstring output of the prior command>
If you get an error post that error.
If nothing else works you can try to post the tx details so others can see if there is a deeper issue by using:
getrawtransaction 76a4640cf4049e81d228f3a3429159ea35c82202dae6c7648b7f091e8b4fb716 1
(note the 1 at the end which decodes the tx)
The other option is to simply wait. The client keeps track of broadcasted txs which have not been included in a block and will regularly attempt to rebroadcast them.