My computer has suddenly decided it doesn't like PDFs. It will give me an error that the file isn't there or I don't have permission. Google has said FU to a good fix.... I started my computer this morning...opened a reloader manual shut it then tried again and it gave me the error. Same for opening acrobat reader directly. If I keep trying it may randomly open. If I get acrobat to open then I can open PDF files...

Anyone got a clue what the fix is?

I tried installing a PDF reader on a Win10 machine, and it wouldn't allow me to set it as the default program, demanding that I use Edge instead.
Maybe you need to re-associate PDF's with Edge (although in my experience, Win10 does that for you - even if you don't want it to.

But I don't know much.

Well it was working before....

Uninstall that shit and use Chrome to view those files.

I use Adobe to open PDF's, if you have Adobe reader or better, then go to start, settings, system, default apps. choose default app by file type, scroll down to PDF then left click and choose Adobe