If you either lose, or have your passport stolen, you will need to report this to the local police and make an application for a replacement passport.
You should contact your country's embassy, consulate, high commission or passport office in the country where you are now for information on how to obtain a replacement passport.
It is possible that there may be a considerable wait to obtain a replacement passport, BRP or travel document. This is not something which the UKVI can influence.
Please do not worry and contact us.