I use a good quality adhesive putty ('Blu-tac' here in the UK) -but avoid the sorts which dry out and go hard- to hold the brown window/door frames onto the Victorian Mansion walls when the tabs have got broken off. It's not totally adequate, but you might have some success with hot-melt glue.
I assume the bits that broke off are too small to join back on?
If you are joining bits of ABS plastic- that's the hard type most PM is made from- you can usually get something as strong as the original, providing the two pieces fit perfectly together (no missing bits or warping);
1. use a cyanoacrylate glue (aka superglue),
2. use a tiny amount because the narrower the glue line, the stronger the joint,
3. 'huff' onto the glue before joining the pieces, because cyanoacrylate hardens in the presence of water and there is some in the air you exhale,
4. hold the parts together for 20 seconds without repositioning
5. leave for a while to allow the hardening to complete
