If your looking to litter train a rabbit, start by looking at
where your rabbit is going to the toilet mainly. Put a litter tray
in that place. If your rabbit it going to the toilet in a place you
do not want it to, put vinegar there, and this should stop your
rabbit messing where you dont want it to. If your rabbit still
insists on not using it's litter tray, buy some cat litter and put
it into the litter tray, this encourages the rabbit to wee there,
as soon as your rabbit is weeing in it's litter tray, take away the
cat litter. If your rabbit changes back to a place where you dont
want it to wee, put the cat litter back. Keep doing this until your
rabbit gets the hang of it!