For anything that is serious enough to be called a 'disciplinary infraction' you should be given a chance to defend yourself against the accusation.
- The first stage of this is to make sure you are given details of
what you are accused of - for example (and I've no idea if this is
in any way what you are accused of) not just "you stole company
property" but "you stole such and such an item on such and such a
date".
- If you are accused of something serious, that might result in your firing or some other serious punishment, read up on your rights according to law and company policy. You might for example have the right to have someone sit with you in any meetings. If you have that right, use it. If you are a member of a trade union or professional association consult with them, and have one of them accompany you to meetings if allowed.
- Once you have the details, and you believe you did not do what you
are accused of, make that clear to your boss. Ask for a meeting to
discuss why he thinks you did this. At that meeting be prepared to give your side of the story. In the meantime, get together
the evidence that will prove you didn't do what you are accused of -
emails, written documents, and find people who will be able to back
up your story. Be prepared to list the evidence in your favour to your boss, although you don't need to have the people who will back your story present at the meeting. If your relationship with your boss is not good, you may want to move straight to the next stage.
- If the meeting at stage three did not resolve things, then you need to request a formal meeting with someone from HR as well as your boss. For something serious you might also want to consult a lawyer. At this stage you are probably going to have to produce any evidence you have to back your story up, and they might also want to involve any 'witnesses' you have.
- If this still does not resolve things, any further escalation is going to depend on law and company policy and we can't help you. There will probably be a company appeal process.
Throughout all this process it is very important to remain calm and professional in tone and attitude. Don't accuse your boss of lying, or bias, or prejudice, or anything like that (unless you have absolutely irrefutable evidence that is the case). Your boss might be acting as best he can according to the information he has been given. It's important not to be angry at any point. State your case calmly and clearly.
If you have been accused of something that might also be a criminal offence, such as theft or leaking company secrets, you should consult a lawyer now.
If at any point you realize that you did do something against company policy without realizing it, even if you think it wasn't a 'wrong' thing, (even if you think it's a stupid policy) be prepared to admit it and make it clear that you didn't realize you were doing something wrong.
Finally, we don't know your company policy, so if it contradicts what we say here, follow company policy. Make sure you know what it is.