I'm a newbie here but when I use private bitcoin wallet I have to copy the file wallet.dat, bitcoin address and private key for it then I save them in USB flash before I can do something in my wallet. it will be safer and restored.
if your using private keys. be warned.
the private key is only connected to one public key.
the wallet.dat only stores the private keys held BEFORE the backup
when you spend funds, most wallets make new random privkeys. so funds will move to NEW privkeys and those privkeys wont be on your OLD wallet.dat.
meaning you have to re backup your wallet.dat on a regular bases.
seeds however use a long entropy pass phrase and all keys are made from that one original passphrase. meaning all keys can be re-established by that seed.
its best to move over to seed based key storage if you are not in a mindset/desire to constantly back up the old style privkeys every time you spend