At what point is it too late?
When have you exhausted every possible avenue for resolving your problem?
Do you have decent backups that you've checked and confirmed work?
Are you tearing your hair out?
Has it been three days, and have you not seen daylight since Tuesday?
Permissions can be tricky and awkward, and sometimes it's just better to say, "Screw it, this system is too far gone, I'm starting again." My general rule of thumb for this sort of thing is how many meals I have skipped trying to fix something, and if it's more than one, that's too many meals skipped.
Before now, I've done stupid things, as I think I've made painfully clear throughout this book so far. I've chmod'd entire systems to 777 recursively (which breaks a lot), I've deleted directories in an effort...