I have never had a problem with my distortion pedal it worked just fine then i dint use it for about a month and now when i plug it in and push the pedal it wont work.

DO NOT USE a guitar pedal in effects loop as it has the WRONG signal levels.

Also, when you boost the gain preceeding a distortion setting in an amp, the amp will just limit out and it will appear that the effects in the amp aren't working... but what is happening is you wind up with too much input signal and the "flat topping" distortion occurs right at the inout of the amp so no further can occur when you select a distortion in the amp.

The first thing I would do would try a 9V AC Adapter to rule out a battery issue completely. But if you have changed the battery already, this shouldn't be the issue. Does the red light come on at all? The next thing I would check involves removing the back cover of the pedal and making sure the input/output jacks are okay. Do you see any hanging wires, loose solder, or smell a burnt smell? If you have only had this pedal for a few months, you may be able to send it back to BOSS for replacement under your warranty.

A few things to try....

Usually the adapter will over ride the battery when used.
1) Make sure your 1/4" cables are working properly without the pedal "in-line".

2) Take out battery, and use just the adapter only. Make sure it is the correct and proper adapter that works with Boss. Usually the PSA-120. If you are not using a Boss Adapter, make sure yours is a direct replacement with same specifications. 9V/200mA. And "tip negative". DO NOT use Radio Shack stuff, nothing against them, but there adapters just don't mix well with Boss products and the like.

2) Try just the battery, no AC adapter. Remember to unplug the input when not in use. Saves battery.

Basic rule of thumb...when using correct AC adapters for all your pedals all the time, and all sounds good, then take out the batteries.

If you still experience problems, it would be an internal IC chip most likely. From there post another question maybe.

Make sure the pedal has the correct power supply voltage, current AND polarity.

Also adjust the setting knobs as needed.

Make sure the in's and out's are corectely connected... it will work clean if they are backward, but no distortion.

This sounds like a broken ground wire or trace within the unit if an IDENTICAL pedal does not act the same AT THE SAME SETTINGS.

Sometimes a circuit trace gets broken on the board inside pedals and can cause this.

Since an identical pedal doesn't have the problem, service is required.

If you know electronics you can open the pedal and look for obvious problems.

HINT: Use a bright LED penlight to "candle" the circuit board to look for cracks.

Look for broken solder joints... this can take an experienced eye to spot.

A distortion pedal NORMALLY is very simple circuitry.

Distortion is a very HIGH gain operation and any hum on the input will be amplified many times.

Check your guitar AND input cable for ANY hum at all at high gain settings on the amp WITHOUT the pedal in line to assure that the source is not before the pedal.

ADDITIONAL cause could be a poor power adapter for the pedal or even a bad filter cap in the pedal.

First and foremost , check your signal chain. By that, i mean put the pedal aside, ...just unhook it and take it out of your signal path. Using the same cables , guitar , amp, other pedals - borrow a friends MT-2 if you can get one , and try THAT to see if THAT works , OR any other kind of distortion pedal. If another one works ok , it's YOUR MT-2. Boss pedals are pretty rugged , but sometimes the little actuator (on/off switch) underneath the treadle (where you push your foot down) will become faulty. That's a high-gain pedal - are you using a basic Strat or other single-coil pickup guitar? If so , are you playing close to any flourescent lights? SIngle coils are noisy around those lights. Will cause a hum / buzz if using a heavy dist. pedal. You can check that by moving around as you play.

With everything switched off. I will surmise that you are using the onboard battery with the foot pedal and not a power supply.
1. Plug lead from guitar/instrument into INPUT side of pedal
2. Plug lead from OUTPUT side of pedal into amplifier INPUT.
3. Turn amplifier volume to about 10 o'clock - to stop blowing your ears out.
4. Turn volume up on guitar to acceptable level.
5. press foot switch on pedal and adjust pedal controls to suit your type of distortion.
6. Play like Hendrix.
Good Luck
ps Just as an after thought rechargeable 9volt batteries are the way to go. I've been using them for years as I always get caught up in the power cable.
If you're going to add another pedal like a Phaser, Compressor, Flanger or what just use small connect leads between each pedal but always, always put the compressor pedal last in the line.

I take it you have made sure that both the cable to the distortion box from the guitar and the cable to the amp are both good. From the description you give, it sounds like there is no signal getting to the pedal. If the cable is good, then the next likely suspect would be the input jack on the fuzz box. Try wiggling it a little with the guitar cable in place to see if it is loose. Some input jacks are unbelievably cheap and flimsy. A crackling sound (static like) is almost always a bad connection. If it was the output jack, I would think that the guitar signal would come through a least a little bit, but you might want to try wiggling that one, too, if the input jack isn't the culprit.

Another possibility to check is the battery, but this doesn't seem as likely. Some effects units devour batteries, especially units that use 9V batteries. I have a multi effect pedal that kills a 9V in about an hour.