My ETH funds were stolen and I am sure I didn't give out or handled carelessly the Mnemonic phrase, JSON file, private key nor the key store. Please I want to know ways by which a cryptocurrency wallet could be hacked.
You probably went to a phishing MEW site.
Or maybe you participated in those scam airdrops that promises to give something if you enter your private keys.
Try to get a Legit Ledger Nano for long term strorage.