I have just purchase your Acrobat Pro DC after my previous license expired, now ALL my document's extensions have changed to .THOR on my laptop, and now I cannot open them, can you please advice.

Also look at

*.thor Ransomware - how to remove?

Was as unable to edit my original reply for some reason according to the forum software

Take a look at the following link. The Thor ext can be a sign of ransomeware on your machine. Where did you install your software from?

https://www.tripwire.com/state-of-security/latest-security-news/thor-variant-locky-virus/