Call the company or bank from which you sent the payment immediately to report it as a fraudulent transaction. They may be able to reverse your transaction.
If you lost money through a gift card scheme, contact the gift card company to make a claim. Tell them it was used in a scam. Keep the gift card itself, and the gift card receipt.
File a report to your local authorities. A police report can assist with your claims to the bank or relevant companies.
If you have provided any personal information to suspected fraudsters, there are specific actions you can take to prevent any further damage. For example, if you have revealed your card information, you should contact your bank or credit card company immediately; they can help you monitor your accounts and prevent unauthorized charges.
More guidance on identity theft can be found here: