Interpol virus

A popup came up on my computer from Interpol/ FBI claiming access to my files was blocked. They wanted money, $100 i think.  There was a countdown clock of 48 hours I believe.  I didn't pay a lot of attention as I was trying to get it closed out and run a scan.  I tried to close out the pop up but it kept flashing back up. Went to task manager and closed it out.  I ran a full Norton Scan and power eraser and nothing showed up. I still have access to my files. What should I do ?

Thanks,

kclc1992