What can I use on my wood floors to brighten them?

I use halloway house products on my very old battered wood flooring. Use the cleaner and then the floor finisher! Looks great

First wash them down with white vinegar and water 50/50 using a microfiber mop.Then once the film is off use the bona wood floor care system

Lightly sand and re-seal or use a Coloured Varnish and then sealer.

https://smile.amazon.com/Rejuvenate-Professional-Restorer-Non-Toxic-Application/dp/B00KS70ARS/ref=sr_1_fkmr2_1?ie=UTF8&qid=1515774447&sr=8-1-fkmr2&keywords=wood+floor+brightener This is a product I've heard good things about:

We have had hardwood floors in our 7 different homes and have used a lot of HW floor products over the years. We stopped using the steam mop when it started blistering off the finish at the seams on a newly professionally installed traditional oil based sealed oak hw floor installation.

The past two years we have been using the BONA mop and solutions and we’re very pleased with the results.

https://us.bona.com/products/hardwood-floor-mop.html

I have used Rejuvenate on my floors and it works great! I had areas on my floors where the finish was actually worn off and this made it look like I refinished the floors. Super quick and easy.