Your visa probably won't work at entry and you'll have to be admitted as a tourist (and start the whole visa process over). That's why there's the annual report and why you have to renew the card every five years — to prove you actually live here. Otherwise it's not really permanent residence, is it? Did you do the report every year? I doubt it can be done from abroad. When I tried while I was in the UK, it failed with a ‘can't find entry record’ error.

I didn't think they could expire, but maybe they need to be renewed every five years?