Cannot believe that you removed a load bearing wall on a two story home without supervision and advice first.
If the second floor is pancaked on the first, then you are too late for this.
Call a professional at once. Throw down your ego and admit your mistake and do not do anything more in that building as you might get seriously hurt.
If you are not listening then get two floor jacks and find the floor joists and place a large board over the area so that the jack will not damage the floor joists it will sit on and supply the load.
you need two 6 x 6 posts taller than the floor to the ceiling. Then you need a 6 x 8 beam that will span the ceiling where the wall was. You need to cut the posts so that they are equal to the ceiling height minus the beams width and the jacks height then start jacking up the posts so that the beam sits on the ceiling where the wall was. Jack up the jacks until the beam is level and straight. Both jacks must be exerting the same amount of pressure on the above ceiling. So turn each jack evenly and slowly, all you want to do is to brace the floor/ceiling and keep it from falling further. then you will later need to get the ceiling and floor on second level flat again.
This is a very dangerous operation and if something slips anyone can get hurt and more damage will occur.
You need a professional company out now to bail you out on this.