What type of flooring do you have? That will influence what you can and should do. Your skill level and determination will also play a part. The staining may or may not be as bad as you think it is once you get down though the surface layer.
I've saved some pretty nasty floors. Just to show you it
CAN be done, here are some photos!
These photos are show a floor I repaired for a customer as part of a historic restoration project of a 9,500 square foot Queen Anne mansion which had been divided into 8 apartments. I was employed to rebuild the interior as it was in 1910. When I arrived all I had to go on was an empty structure, a few photographs and odds and ends of trim which did not make it into the dumpster.
The floor is 1/4" by 1 1/2" White Oak strip flooring with Walnut and Maple parquet and is at least 80 years old, judging by the manufacturer and flooring plant location which was branded on the back of each strip.
The day I arrived:
Repairing parquet in the adjacent room:
In progress. Old, damaged mouldings replaced with new, made on-site.
The day I left:
I reproduced all the mouldings and trim work, plus some windows on-site with a mobile woodworking shop.
One of several sets of custom knives, ground to match 100 year-old mouldings:
One of the test samples I used to set up the machines. Material is Poplar:
Newly made on the left ready for rubbing out, original moulding from 1910 on the right. Try finding this stuff at Lowes!