Licence is valid for
5 years, it does not matter if you have flown or not for it to still be valid. Just because you have a valid licence does not mean you can fly a single engine a/c solo, for this you need a current SEP
rating which I suspect is what you really mean when you say your licence has expired (though do check your licence expiry date), not having flown for so long you need to do the skills test as Backpackers post says, you will also of course need a current medical.
