@GrimyVillain,
The only way to be absolutely certain the system is free of malware after an event like this is to perform a full system recovery which would result in your data being lost (be sure to backup important data). You can also run malware scanners as suggested, but they don't always catch all types of malware. If it were me, I would change my passwords to any pertinent accounts and take any necessary precautions such as notifying your financial institutions to be on the safe side.
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