Can someone help me with my hair dye disaster?!?

When I was younger, I had bleach blonde hair. Unfortunately, as I get older it gets darker. I dyed my hair but I didn't leave it on long enough and now it's strawberry blonde! It doesn't suit me and I wanna get it light again. To make it worse, my dirty/ashy blonde roots are coming in. It looks a right state! How can I get it back to my really blonde hair again without dyeing it? Or will I have to grow it out? Thanks.