We opened are windows while putting on second coat of poly, dirt and dust blew all over, Now its dry and the floors feel like there is sand everywhere. How is the best way to fix this? Should we use sandpaper, steelwool, or just carpet over it..This project has been a nightmare

These are just a couple of reasons that you probably should have hired a pro. I would suggest buffing the floor with a 220 sanding screen and applying another coating.