Does toner still work on medium blonde hair?

You don't need to bleach again before toning, if you make your own toner it will help cut down the brassiness of your current shade.

Since your hair is already bleached don't use a toner that needs developer, especially if you plan on lightening your hair further at some point. Protecting the health of your hair is important. For the same reason you should not use a blonde box dye, the results are unpredictable and damaging.

You should get a blue toned purple dye such as directions violet and mix it with conditioner to make a toner. I would start by making it really weak, doing a strand test and adding more dye to the mix until you are getting the toned effect you want.

Also many people use silver shampoos such as bonacure silver shampoo left on for between 5 and 15
Minutes to tone their hair, which would be an option if you don't want to mix your own toner.

Thanks so much. I will do just that. ;D

I second everything Marthakins suggests.  I fully agree to mix your own toner (a semi and conditioner) because sometimes those that are sold specifically as "toners" might be a bit weak in saturation and not do the job well enough, and of course all they are is a mixture of, well, a semi and conditioner!

If you mix your own, you can control the amount of dye you use, start more diluted and add more dye as you see fit.  That will definitely work better than buying a ready-made toner and will last loads longer as well.

If your hair is very orangey, a purple based blue diluted is your best bet, Directions Neon Blue is a good base for mixing toners.