Just to let you know, I managed to sort it.
I somehow managed to open firefox on the laptop and found the following site:
I downloaded the EXE File Association Fix
and it worked. :) Managed to do a system restore (back to the point before the last one. Everything seems to be back to the way it was this morning now.
(I am typing this from the laptop)
Cheers for everyone's help/input. First time I have used this site and although I hope it's the last, I know where to come next time I run into problems.