Re: I have my wallet.dat from a backup but I can't remember my passphrase
I still thinking that my wallet is corrupted. The file seems damage. Like i said i always had a possibility to restore an old version of my wallet.
What do you mean you "always had a possibility to restore an old version" of the wallet? 
Do you mean you were able to restore old versions of wallets when you were using a different wallet application? (like Bitcoin Core etc)Quote
Here I can't or maybe there is a way to restore the old file with the previous password ?
It's pretty simple... you either have a backup of the old file with the previous password... or you don't. Do you have a copy of that file stored someone like on a usb drive or other backup media? If not, then there is no way for you to magically restore this fileI'm still confused by a comment you made earlier where you said:
3 / I know that's strange for my seed. I try to swith servers, i try everything and nothing works... And I'm sure about the seed because like i said, i recover one of the btc adress. It's green on the corner everytime.
If your seed was recreating a wallet that has the same address that you previously had... then there is something else that isn't working right.Quote
I found someone to buy my wallet for 2 btc... I don't know if i can accept.
If the amount that is in your wallet is even close to 2 BTC... sell it! why is this even a question? 
And if you do sell, just remember to use an Escrow service! I'm guessing your wallets has more than 2 BTC in it?