lost passport and overstay in china what should need to do to comeback to philippines

Do you have a copy of your lost passport? Either way go to the Philippine Consulate, if you have a copy of your passport will be easier to proove who you are, they will prepare a Travel document.
Then you have to go to the local police Station, they will put you in detention for 10 days, ( no fine) it's not a jail just a detention center... once you are out the Police will issue a visa to exit China with your travel document done by the consulate... Then you must exit the country within 10 days.
If you dont have a copy of your passport the consulate will tell you what you have to get in order to process your travel document...or they may have to request your birth certificate.
Hopefully this is useful.
Marisa. Shanghai