I wanted to know if anyone has an answer for me. If i still have my public/private key, can i withdraw the BTC that i previously put into PlusToken using those methods since Plustoken has shut down?
The money is gone. PlusToken was a Ponzi Scheme that collapsed and the high-level scammers run with the money. They signed a Bitcoin transaction with the message "Sorry, we run".
So as you can understand there is no way to get your money back. Any cryptocurrency you send them was sent in wallets controlled by the scammers and most of the BTC they extracted have already been sold through various OTC desks. Sadly the money is gone. I understand that it is frustrating and I don't know if there will ever be justice delivered on this instance.
You need to move on and never trust anyone, especially projects that guarantee high returns.