well dear... if were in some country like, where you entered on Visit based visa, which you get on the airport. as in japan.. there are so many countries citizen who gets 3-7 months entrance pass without a visa. including USA, Turkey, Brazil....after the end the duration. you have to apply for the proper visa or leave the country within a week after the expiry of the pass . and let suppose you don't leave the country after the expiry of the pass and also don't apply for the visa, and stay in the country for 3-4 5 years what eva. at the end when you want to go back to your country, simply go the police station. tell them you were staying the country as on illegal status, they will verify, whether you were in some illegal or some criminal actives or not..if you were. not.. they will put you in jail for like 1-2 weeks and then will deport you from the country. and will hand over to you to you country from where you belong. As if you are Pakistani. they will handover you to FIA, Don't worry.. FIA is like our desi Police. Usaly they take few thousand and won't ask you a single question and release you.
Don't worry if you are living in some country as non-criminal visitors with no visa. then just go the the police station, they will get your way back to the homeland
well you can enter in Pakistan without a passport. All you have to do is.. just prove that you are Pakistani citizen, you can use your CNIC for entrance;), tell them at the airport, you have lost your passport