The first and the most important thing is to remove dirt or grease from the damaged area by cleaning it thoroughly.
Now you need to use an epoxy filler to fill any deep scratches, cracks or holes. An epoxy filler is not very expensive and can easily be bought from a hardware store.
Once you have used the epoxy filler and feel that the spaces have properly been filled, you need to remove the excess filler with the help of a clean and dry cloth.
You now need to wait and let the floor dry. Take sandpaper and sand the epoxy filler so that it settles smoothly down to the floor's level.
Now, in order to conceal the damaged area, you need to use paint, which matches the shade of your epoxy floor. If the colour is the same, no one will ever notice any difference on the floor.
The floor will now need cleaning after the paint-job. Begin by sweeping the floor well, and if it is a garage floor that you are working on then you might need a leaf blower to clear it.
Now take a scrub brush and a de-greaser to scrub off the stained areas. After scrubbing, wipe the floor with a damp cloth, but make sure that the cloth you use is clean.
To finish it off, you need to use ammonia and mop the floor with it. It is advised that you mix water in the ammonia to dilute it before using. You can now either wait for the floor to dry naturally or wipe it thoroughly with a dry cloth.