Can’t he change the format of the files or you can’t? Just curiousYour computer is infected with ransomware. You will be able to get rid of it, but you won't be able to de-encrypt all those files - and I do not recommend that you following the instructions in the text and pay any money.
Those files are gone for good, I'm afraid. To protect any future files, invest in a good antivirus program and use Malwarebytes too:
Read this:Can’t he change the format of the files or you can’t? Just curious