Dear Sir or Madam,
What type of idea was it? How did you communicate this idea? Generally - ideas alone are not protectable. However, you may be afforded some intellectual property protection if certain requirements are met.
I look forward to hearing more about this case.
-Tomas M. Flores, Esq.
Not burning bridges is always good advice, but ideas that develop into marketable products don't come along everyday so you need to enforce those that do make it into production. Hopefully, you kept some proof of your transmittal of the idea so that you can prove that you did not create something after the fact. (even better of course would have been a confidentiality agreement with the company where they directly promise not to make any use of the idea without your permission). In any event, you need to take whatever proof you have and get a free consultation with an attorney in you area who practices intellectual property on a regular basis.
If, at the time you disclosed your idea to the company, you took reasonable steps to keep your information secret and the idea was not readily ascertainable or generally known to competitors and the public at large, you may have a trade secret. Reasonable steps depends upon the sophistication of the customer, but generally necessitates a non-disclosure agreement. The aforementioned tests should be confirmed with an attorney evaluating your specific situation (more detail than given). As far as proving that they didn't come out with it independently or reverse engineer it, they would argue why would they wait 10 years? On the other hand, if you have it in writing that you've been told "not to burn bridges", that you should accept that they stole your idea, that's powerful evidence. Oral evidence of the same is helpful but less powerful.
There is nothing to do. If you had an invention 10 years ago, you should have applied for a patent instead of giving it away for free to a company.
Unfortunately, that's the only thing one could say about your question as it is - could you provide more details about what industry the company is in, what kind of idea you submitted, whether you actually had an invention or just an idea, etc.?
**This post does not constitute legal advice, nor does it create any attorney-client relationship between Sadiq Ansari and any other individual or entity.**