Can anyone tell me what is the best way to deposit money into Liberty Reserve that is not a scam?
I can not use an exchanger because i do not have any money in any pay processors.

You don't have to have monye in other payment processors other than Liberty Reserve to fund your Liberty Reserve account. E-currency exchangers accept bank wires, credit cards, and maybe have some local options for your specific country. Take a look at e-forexgold.com, this is the oldest exchanger, known for its reliability.

You can use Paymentmedium.com to ad funds to LR and you can fund your Payment Medium account via WU, Bank etc

We can offer you our service, we offer various payment methods. To fund LR-account you can simply send us a bank wire or WU/MG transfer. We're on the first place at the official LR exchangers list - you can check it on their site.

How can know if an exchanger site is not scam?
is there any lists of the legal sites?

Use official exchangers listing www.libertyreserve.com/en/exchangers