If the following screenshot looks familiar (enter the fake antivirus scareware), then you may be entitled to a refund.
From the FTC:
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Starting this week, more than 300,000 consumers who were victims of a “scareware” scam will receive refunds resulting from Federal Trade Commission settlements with Innovative Marketing and other parties involved in the scheme. Several defendants agreed to surrender more than $8 million total in ill-gotten gains to settle FTC charges that they used deceptive ads to trick consumers into thinking their computers were infected with viruses or spyware, and then sold them software programs such as Winfixer, Drive Cleaner, and XP Antivirus to “fix” their non-existent problem.