help! i pulled up the rugs in a house i'm buying & found unfinished wood floors id like to finish them, there smooth so im not sure they need sanding or just a bleaching process or just stain & polyurathene the floors about 45 years old thanks for any help linda

Laura,
If I were you, I'd ask a local wood flooring contractor to come over and have a look. If the floors are as you say (level, sanded smooth and unfinished) then all that would need to be done is a good screening. Then one could stain and finish the floors. However, I think you need to verify the the condition of the floors. Good luck!

If your floors are as nice as you describe, they could be made to look like new with a complete sanding and finishing. A screening and coating will not get down to "new" wood. There are generally shadow marks and other discolorations from being covered up for so many years.
I usually drum-sand to level cut these floors, then use a full trowel fill on the entire surface of the floor to eliminate minor spaces between boards, and holes from tack strips. Successive cuts with the sander using finer grits and screening prepares the surface for a good finish. The results are worth the price.