I know people don't like having the blindingly obvious suggested to them but the following do have to regularly be said to people I know so:
Have you tried turning it off and then on again?
Is it plugged in properly?
What does the manual say?
You can probably Google that
I know you remember making the food but did you actually eat it?
Well do it sitting down then
You're probably having a reaction to one of the ingredients, read the label and see if there's anything in there that you recognise
Okay did you actually tell him that? With your mouth? Using words?
The painkillers only work if you take them
Cool had has self-flagellating actually made this work before or?
Yeah okay you 'must remember to' but you remember to NOW so do it NOW
Put it in your fucking calendar
Do you want me to show you how to set up reminders
... the suggestions of the blindingly obvious will continue until people demonstrate consistently that they don't need it.