I'm not sure about Hungary and I can't find anything specific on Google. However, as a guide, the UK says that PR expires after 2 years outside the country. For Canada, if you are outside of Canada for more than 3 years in any given 5 year period you lose PR.
I guess that these would be good estimates. If you were outside Hungary for longer it might have affected your PR.
However, if you are still eligible to hold PR, you would be able to take advantage of whatever it offers to you inside Hungary. I'm not sure how PR will affect you outside Hungary in other EU countries. See here for a discussion:
http://community.expatica.com/forums/to ... work-in-eu (it's a little old so you might want to keep searching).
Sorry...not sure.