You probably logged in to a phishing site and typed all of those private keys you have for MEW and your wallet ID & pass for blockchain.com
Do you remember those websites that you visited and required you those delicate info of yours?
i remembered last few weeks ago i encountered clipboard highjack, everytime i paste my wallet different wallet address appeared i aware about it so i format my laptop. then after formatting the clipboard corrected but when i checked my MEW wallet and the BTC wallet all balance withdrawn.
You have downloaded the malware and I think it has affected your wallet and balance already before you formatted your laptop.
Do you remember any software you have downloaded? sorry but there's no way to get those coins back.