Sorry i open a new topic only for this can anyone tell me if i can still import the wallet.dat from bitcoin core to blockchain.info i can not see the future anymore i need to format my pc but i am worried that i can not restore it to bitcoin core later i like to have the coins on blockchain while i do this
This is rather confusing.
Wallet.dat = the file containing the private keys in a format usable by bitcoin core. If you backup this file, you can easily re-install your pc without losing your coins (you need a VERY recent backup, since bitcoin core generates new addresses all the time).
Blockchain.info = company that lets you generate online wallets.
You can export all used private keys from bitcoin core and import them onto blockchain.info, but i wouldn't recommand it. The other way around: you can export your keys from your blockchain.info wallet and import them into core (not really recommanded either)