My advise is to install some nice new laminate! I have attempted to restore old pine flooring, and in most cases have found its not worth the effort.
If you want to proceed, check for lead content. If lead free, then rent a drum sander, and buy plenty of replacement 80-grit paper. Use the coarse to remove the paint and most wear damage, then use finer grades to finish. Pine floors are soft and will not hold up to dogs, heavy traffic, appliance moving, etc. Finish with Polyurethane, and enjoy for a year or two… or just get some wood or laminate floors and save yourself the effort.
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