Yes yes put everything from the floor into a big bag/box (or several) then sort one out at a time. What you really need is a place designated for everything.
So if you keep putting certain things on/in one cupboard and it is in the right place for those things, then make that the specified place to put them. Once you know where things go you are halfway there.
Second stage, once everything is in a box: take first box, surround yourself with a carrier bag for each room. Take things out of box, and place in correct carrier bag.
This is what I like to call designation.
You can do it all a step at a time if you are pushed.
Third stage: take carrier bag which has now arrived in its destination room, and sort all the bits from it into their correct place/cupboard etc.
At each stage if you have things that do not HAVE a room/place then keep them back in a separate bag for 'lost souls' and decide them another time.
Also have a small bag for crucial bits you find that you need NOW, put money, batteries, keys etc in it so they don't get mixed up in the jumble again.
The hardest part of sorting out is the mental work...making decisions re things and where to put them. That part can be mainly instinctual though, as I said before - if things tend to end up somehwere particular, then that's going to be the best place to keep them (leaving aside the ice lollies behind the radiator )