I've posted this elsewhere but I thought it should be posted here too.
Guys, I have to share this in case anyone else has the same problem I had.
On one machine LastPass and AdBlock Plus both stopped in working in Edge and after trying to reset them, then tried the Windows Store Trouble Shooter, all without success I uninstalled them. Well, I found I couldn't sign in to the Store either.
A quick Google search and I found this:
http://www.thewindowsclub.com/reset-windows-store-cache
Worked like a charm and definitely worth remembering!
I hope it helps someone else too.
Cheers!