There are some stains that you just can’t do anything about. This is because you have not added something that is causing an unwanted colour or odour, but because you have removed (or damaged) the thing that is producing the colour that you want.
Almost exclusively this is referring to things that have been attacked either by bleach or acid. If you have spilled bleach onto something that has discoloured it, then unfortunately there is nothing you can do. The process of bleaching is irreversible. Bleach (section 6.1) is an extremely strong oxidising agent that will destroy most pigments and dyes (particularly in clothes) and will irreversibly discolour some types of kitchen bench tops (particularly cheaper type synthetic laminexes) and paints.
The bottom line is this – if bleach has caused the problem then nothing will fix it. Sometimes if you are lucky you can restore the surface by physically removing the first few layers by mechanical abrasion (see stain removing strategies) but generally it will never be what it was. Another approach that may have some limited success is to attempt to steam out as much as you can. Place a cotton tee shirt or paper towel over the damaged area, then put your iron on top and blast it with some steam. With a bit of luck you may remove some of the staining.
The same is true of acids. The two strongest acids that are encountered by the general public are hydrochloric acid (otherwise known as Muriatic Acid and freely available from hardware stores) and sulphuric acid (battery acid).
Both of these chemicals will vigorously attack anything metallic, and if you spill them on pavers, particularly those of a darker colour, they will discolour them irreversibly.
The take home lesson from this is that bleaches and acids, although they can be useful stain removing chemicals, are very strong chemicals and must be handled appropriately.