Well, ever since I got a wah pedal(VOX) in christmas, every once in a while, i will be playing my VOX AD15VT XL Valvetronix amp, which is about a year old, and the tone/sound of the amp will turn to a clean, mildly distorted sound that is not affected by any bass, mid, or treble knobs.
The knobs that change effects still work (flanger, phaser, and rotary), and knobs that change the style(?) of the amp (like going from molten to funked) still kind of work.
The only solution to this which only works SOMETIMES is if i plug in my wah pedal to my amp, turn the wah pedal on and off a couple of times, then take out the wah pedal and put in my guitar and then the sound will be responsive and unique again. However, this only works SOMETIMES, and it isn't permanent.
I know this is a really vague and weird question, but if anyone could help me, it would be greatly appreciated.

P.S. If anyone actually has the same amp that i do, basically my amp will sometimes only give out a sound that sounds like the preset one on the knob "black", and knobs like bass, mid, and treble do nothing to fix it.