LYCKSELE LOVAS mattress cover (Oakland)

I have a sofa bed from ikea called LYCKSELE LOVAS. I took the mattress cover off of the foam to wash it, and somehow it got lost.
Does anybody have this sofa bed in which it's foam mattress died but the cover is still good? To be clear, it is not the cover for the sofa that I need. It's the zip-on cover that goes directly on the foam/mattress.
FYI, I already tried to get a replacement from IKEA, and they don't sell or replace it.