I'm Losing What Little Was Left

I didn't have much of a mind left to lose, but I think I'm pretty close to having NOTHING left!! This upgrade -- holy crap!! I have seemed to left myself with no individual pages accessible. Used to get a "Forbidden" error; now I'm getting a "so-and-so category doesn't exist". You wanna bet?! They all exist! They're hiding somewhere and I can't find them. Well, not the categories themselves; I know where THEY are. Browsers just can't seem to find my archives. HELP!!