LOL. What if there are lots of files, applications etc. that needed to be backup on the system? Are you willing to spend time on it because of your own mistake why your coins loss? It's hard to reinstall all programs from a scratch especially if you already have lots. And besides, the computer itself is not the main subject.
Based on OP's statement, it's clearly his fault and no one to blame here but OP itself. He got a notification on email and I assumed it was redirected into phishing something.
But what I can't understand here is, OP is holding a decent amount of money and 150,000 NTK is worth BTC4.7 as of the current exchange rate and yet OP doesn't know the simple and basic precautions to make the wallet safety?
To OP, no way you can changed the seedphrase. Create another account from scratch and transfer all your remaining funds there.