Denied Access to my own data

Avast has encrypted my documents using the “Protect sensitive data” function. I had copied my “protected” data to an external hard disk and then rebooted the computer and now I can no longer access my data. I don’t know if the data is really encrypted or locked in some other way. I can’t get a proper answer from the official Avast support. Is there any way to “unlock” the data myself? Would be very grateful for any help