First you should decide how important it is to you to have nice hair. It is going to be worth it to go to a professional who knows how to deal with color mistakes. It might cost you some money but how many times are you going to try to fix it yourself, damaging it more in the process, until you have to break down and pay someone to either fix the color or cut off all your damaged hair?
Don't bleach it! You still have all that highlighted hair underneath the red color and if that gets overprocessed by over bleaching it, it will not hold any dark color that you put on. Hair does not repair itself like skin does. You can definitely damage it to the point of no return and a sure fire way to do that is to bleach it multiple times.
The easiest, and most gentle, thing to do now is get a semi-permanent color that is the same level of brown (or darker) in an ash. Since you used medium brown, a medium ash brown should work. This will tone down some of the red and not make it too much darker.
The brown you used turned red because you put it on blonde hair. Going from blonde to brown is touchy....there are steps you have to follow to get the right color. I obviously won't go into that here, but that's why when doing such a drastic change it's smart to spend the money at a salon where you know they know what they're doing.
Good Luck!!Hair Color Correction HELP!!!?
Unless you used temporary color you cannot just wash it out, it is called permanent color for a reason. The only way to go lighter is to bleach. Since your hair is so red you will need to bleach before you tone, a toner won't tone out such an intense red. Shampoo your hair a lot with a cleansing shampoo and hot water, that will fade it as much as it can be faded. If you get a salon quality cleansing shampoo you will probably get enough out to just tone it. You'll need to tone it with an ash dye, but again that cannot be done over the red unless you are dying it black.
