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?
Sorry to know that, but, Plustoken is a scam. A scammer will never give your money or BTC back.
You can read some articles that state about this very huge scamming, structured, and also like-legit project scam.:
https://cointelegraph.com/news/plustoken-scam-moves-123m-in-bitcoin-just-as-btc-price-regains-10khttps://bitcoinmagazine.com/articles/how-the-plustoken-scam-absconded-with-over-1-percent-of-the-bitcoin-supplyhttps://cointelegraph.com/news/plustoken-scammer-implicated-in-chinas-second-ten-figure-crypto-ponziYou are not the only one victim, they scam a very huge amount of BTC, in 2019, the total scammed was around 200,000 BTC, what's about now? i think it is more.
So, if you are a victim of Plustoken, You must be brave and give up all of that. And of course, make this experience a very valuable lesson to be more careful when you want to invest. In whatever cases, not only in BTC investment