I have a bedroom with hardwood floors and it seems that some of boards are loosening up. I am not sure if this is something that I can fill with some sort of material or if it has to be replace? Please note that I have never worked with hardwood floors and all the help that I can get is greatly appreciated. Pictures of the damage:






Again, thank you for all the advice.

Is it just me or does that look like the wood is just face nailed to the floor joists? Anyhow, pull the base and pull the wood. Thos loast rows are usually only face nailed. Then buy a cheapo hardwood floor jack and jack them tight and facenail again with larger finish nails.

Looks like your in need of a refinish also.

Looks like there was or is a moisture issue in that area. If so...be sure the problem is rectified, ( kinda looks like it was topical). Then, remove damaged strips, lace in new, sand & finish.