I saved a copy of my wallet.dat as a backup, i used it to transfer 1 btc to another address, now it's got 1 btc less in the total. now I deleted the wallet.dat and open the wallet with the saved wallet.dat before the transaction, I can see a higher balance(it not showing 1 btc off). how could it be? do I lost my whole balance from not saving the newest wallet.dat?
Ack! You certainly could have.
When you send bitcoin, the "change" is returned to an address that you have not previously used to protect your privacy. If your
wallet.dat files doesn't contain any unused addresses, a new one is generated and the corresponding private key stored back in the
wallet.dat file. If this happened, and you didn't save the new file, you may not have the address the change from that transaction was returned to.
I believe that newer implementations of the bitcoin core wallet make this much less unlikely.
The important thing you should clarify is if the address to which you transfer your BTC belongs to the same wallet or another one.
A wallet is just a collection of addresses which have been created by the same Private Key/Seed. In case you created a new address from the same key (belonging in the same wallet) then You should see the BTC you sent in your balance (minus the transaction fee).
It is also possible that your transaction has not been processed yet.
Without additional information we are unable to help.