I get a white screen

[veganline]

I could use Prestoolsuite until recently but now get
- white screen
- same if I press control+u for the code
- same if I install the module to refer me from back office
- same if I type likely fileneames used in the past into the browser.

Recently I was prompted to enter the domain from which I search (or something like that) into the program and did not, so maybe that's the problem.

Is there something I should do?
I have tried reading the instructions but not found the right bit.
kind regards
John