Ok thank you guys! I will try to handle all this!
Well I'm on a mac F... I don't have appdata, and my bitcoin folder only contain Portfile, so I'm a bit lost I don't know anything about all this
If you are not a heavy bitcoin user then I would recommend to you to migrate to a lighter client.
For example
Electrum which is also available for OS X.
The advantage is that you don't have to download the blockchain thus usage is almost instantaneously.
And that you can recover all your bitcoins from a seed that you can write down or memorize when you create the wallet.
If you want to migrate I think the easiest way would be to send the bitcoins from your bitcoin-qt wallet to an address in your new Electrum wallet.