Microsoft Made updates for Severely outdated Operating Systems. I Don't Just Recommend ney I am telling you. Update your PC now! you'll need it unless you want to loose everything.
In the past I have tried with the best software tools, the best hash, translators, extraction software to recover the keys and files needed, etc to un-encrypt these things. It has a 80 to 90 percent failure rate. The only ones I was able to help were the people that had multiple backups.
Even though I don't like updating microsoft products myself due to their issues with um,, well lets say getting it right for hardware, or not breaking excel, outlook, or other various things, I always make sure it's Done!
OS's to Update that stopped getting updates?
Be safe and don't open anything funny from people you know or don't know such as fake invoices, or documents. And don't follow links unless you verify by hovering over the link it goes where it says it goes!