Is it a warranty item or a mishap? If it is a mishap there are plenty of choices doing an internet search.
Here is the first relevant one I got.
https://www.recpro.com/rv-windows/
Wouldn't hurt to ask Jayco if they would sell you one as well.
Most RV dealers would also be able to get them.
Edit: They should conform to industry standards so they all should be interchangeable.