How do I restore my wallet when I format my PC?
Or is there no web wallet?

@hs807 That would be OK. Just be aware that sending funds to different machines will give you different addresses in every copy of your wallet. So you shouldn't have one wallet.dat and use it on multiple different machines unless you understand what you are doing,

@c4 Create a wallet to multiple computers Do copying the original wallet.dat file have no problem?

@hs807 You must make a backup of your wallet.dat file. Go to your QT-wallet and in the File menu select "Backup Wallet". The save that file and make sure you never lose it.

Copy it to two USB sticks etc. Losing your wallet file mean you will lose your funds. There is no way to recover them.

Then you can reinstall your Windows system and copy over your wallet.dat file from whatever backup you have.

I don't know