Hi my roommate moved his furniture and scratched the floor (a deep scratch). He tried to fix the issue by sanding away the scratch. Unfortunately the result was worse than the scratch. We tried to apply polyurethane but for some reason the floor appears darker and not glossy. Any idea on how we can fix this?

sand it fully and refinish it..you will never match that finish.

Hi thank you for your kind reply.
Should we try to sand those tiles with grit 60?
What would you recommend to finish it?
Thanks again?

Looks like white oak

Waterbased finish without a sealer, will pull the tannin out of the wood.

I would mask boards, hand sand good with 60 to get the finish mostly off, then 80 grit to get the rest of the finish and then hit it with 100 grit to finish it up and close the grain a little. Sealer and 2-3 topcoats of finish.

If you are staining and then finishing, you don't need the sealer. Just make sure you wipe the stain in and wipe the stain that didn't absorb off, with the grain, not across it.
If you are trying to use a tinted finish, throw it away.(minwax)

Thank you this is terrific.
I will let you know.

Hi one last question what water based finish w/o a sealer would recommend?

A quality manufacturer. Basic Coatings, Bona Kemi, Poloplaz. Using their compatible stains or sealers.

Post pics when you are done!!!