Help me my hair is ****** up.....?

I dyed my hair only twice one with blonde highlights the other I dyed it blue... those were spaced atleast a year apart, when I dyed it blue I bleached it a lot!.... uhmm so yea my hair is dead now, and I wanna re dye it because its like greenish now I wanna dye it black I have done anything to my hair iin..... 4-5 months? so would it be okay to dye it or should I just wait for it to fade out and then dye it? also is there anything I can do to give my hair "Life" again? i dont wanna shave it... my roots are about 4 inchs long.