While open I would replace the nylon cambelt if worn (usually around 60k miles or above). I always prefer cars with a metal chain, that lasts a lot longer.
As for engine not working, you always check the three things...
Fuel system..is fuel getting up there, check fuel filter, pump, etc,
Air...check air filter and ducting,
Spark..check ignition system.
Also advisable first check for any electronic issues.... check with an OBII reader and connect to diagnostic socket, and check for fault codes.
PS....If you do not have a OBII reader you can get a cheap one on Ebay around a tenner. This is the one I have, that gives the codes, can reset engine managment light, and you check the codes on the internet to see what the fault is in english...(dearer ones do that for you, ie, not needing to access the internet to get code description)
https://www.ebay.co.uk/itm/OBD2-CAN...352528?hash=item342c1c5090:g:EToAAOSwNHVfBK3H