Bitcoin transactions are irreversible, so you can't get them back
But if you know HOW it happened you can prevent a future occurrence.
How do you usually access your wallet? Do you use the website on a PC? Or a mobile app?
Were you given a seed phrase (a set of 12 or so words)? How did you store the seed?
If you're using a PC then you should do a full scan of it for malware.
Phishing is missing from this list so I'll also ask: did you click onto a link (maybe from an e-mail) to log in to your blockchain account?
No, as I recall, I passed not what links. This wallet is open to me for a long time and there came a reward for mining, yesterday it formed 2000$ at the rate and they were transferred to another address. I've raised this amount(