Parents’ leaking rooftop

Hi!
My name is Michal and I am a student. I also work for a living but I do not earn enough to help my parents to collect this amount for a new rooftop.
The problem is that it lost it's guaranty few years ago and has started to leak. Both of my parents work, but my mum is invalid and can't work in her profession so she doesn't earn too much as well as dad doesn't since he lost his 1-person company. To get 4000€ they have to work... few months but they also have to pay bills and buy food same as all the people, so it is hard to collect such a big - for us - sum. Anyway my parents are very helpful and take full care over my granny since my uncle has stopped to visit her plus my mum works for a local charity after work.
We moved outside of a city many years ago and we have a very small house so also a rooftop must cover a tiny surface. It is in a terrible condition right now... So I would like to help them but I can only go to grocery and buy some stuffs.
Thank you all for every cent!

Here it is, our lovely home's rooftop that we try to fix :)