After Update C Drive All Files Disappeared

I am running Windows 2000 pro on an old Compaq. Norton was up-to-date just before problem started: Before Xmas a windows auto update came through. I shut down before it had completed. When I turned on next morning, a sort of error message came up - "would I like to log on in any case", sort of thing - and I stupidly pressed OK. Next thing, everything on the D drive was fine, but on the C drive all my files had disappeared. Icons up as uusal, but most of them did nothing when you pressed them. I can access the internet, but no way can I get into Outlook Express. Event log only shows one error which is OMCI failed to load.

Spoke to Norton to try a remote scan, but the PC would not let me lower the security settings to allow this - just kept bouncing back to medium security level. Gave the PC to a local "Specialist" who acheived zero. Im sending this on my old PC. I really do need my old files back if possible., rather than just buying a new PC! Ideas please (tailored for a compete non-techie)!! It occured that I could create a system restore point (perhaps on an external hard drive) and then start playing in the registry, but am a complete PC moron so am rather (very, actually) nervous about that.