My question is is there any way or anyone experienced who can help or guide me and is there any chance to sell this wallet or use it in any way.
IMO the only reasonable approach is attempt brute-force
if you know how he usually create password and the possible combination is relative low. Even if the possible combination is too much, you can try again in the future when hardware is much faster for brute-force.
Personally i don't recommend to sell the wallet file, since i believe world of selling/buying/trading wallet file as something shady/suspicious.
I'm curious how OP concluded the wallet has 19 Bitcoin, unless there is a wallet address on that same folder but you can't be sure if the address belongs to that wallet.dat, you need to open the wallet to comfirm.
Not all parts of wallet.dat is encrypted. I would speculate OP either sync Bitcoin Core or check the address on Bitcoin explorer to know the balance.