Yesterday as usual i checked my address balance with blockchain and found out half of it had gone to an address i haven't seen or know..but i restarted my core client and the balance was fully there..
then i sent all my coins to a new address and then transferred them back finally blockchain shows correct balance..
Can someone please tell me why blockchain.info showed a balance and a transaction which was not and did not happen?
They had problems with their database in the past. I dont know what happened, but I suspect they have problems again. Blockchain.info is just one blockchain browser, its not
the blockchain. You can also try e.g.
http://blockr.io/ or
http://blockexplorer.com/If you suspect that your data might be compromised it would be wise to make a new wallet with a clean machine and transfer the coins there. Just to be safe. Or use a properly generated paper wallet.