Oh Dear! It really has been one of those days, hasn't it? Bad luck KG but it's not serious if you have AC Reader installation disk to hand It's time to uninstall and re-install. That ought to sort it.
Acrobat reader is provided free on almost every Program installation disk that has a "PDF" Installation or User's Manual File.
As I have no doubt you are well aware.
Cheers, fob.