Speed determines what is recoverable. Call the institution that moved the money — bank, card issuer, or wire provider — and ask specifically about a dispute, chargeback, or recall; many of these windows close in days or weeks, and wire recalls work best within hours. If cryptocurrency was involved, report the transaction hashes to the receiving exchange's compliance team while the funds may still be on the platform.
Then report the crime: the FBI's IC3 and the FTC in the US, Action Fraud in the UK, or your national equivalent, plus the securities regulator for investment fraud. Preserve everything — receipts, emails, chat logs, wallet addresses, phone numbers — because every formal channel runs on evidence. Finally, expect the follow-up scam: unsolicited recovery offers after a loss are common enough to be treated as a default.