@user9968 , your question didn't contain the relevant information required to answer it.
You're a person. If you create some code, then absent any contracts or agreements stating otherwise, the copyright on the code belongs to you.
However, the most common situation is that developers have signed contracts which transfer copyright of their work -- the most common example is the employment contract -- see more below.
The obvious questions are:
- Which contracts (if any) have you signed, and what do they say?
- Have you done anything to inadvertently, either implicitly or explicitly, transfer copyright (or reasonable assumptions of having copyright) to someone else?
Regarding your contractual obligations: Read Joel's answer about copyright for software developers first, and then have a look at your current and past employment contracts, partnership contracts, freelancer contracts, etc.
Regarding inadvertently transferring copyright, that's a little bit more complicated.
- Have you written the code on a corporate laptop?
- Have you checked it in to a corporate SVN/Git repository?
- Have you made headers in the source code with "Copyright 2011 Company Name"?
- Have you written emails stating that the company has a ready product, a product that could only be your code?
- Made any verbal agreements?
If the answer to both issues above is a "no!", then you're in the clear -- the code you wrote belongs to you personally, as it does by default.
Important: The above is not qualified legal advice, and you really should go see a lawyer.