Well it appears you have the copyright to this work (composition) and perhaps there are one or more people that have copyright rights in the work as well because you mentioned that you wrote "most" of the work. In the United States, a composition written by two or more authors is generally deemed to be a "joint work," which is defined as "a work prepared by two or more authors with the intention that their contributions be merged into inseparable or interdependent parts of a unitary whole." Ownership of joint works is presumed to be shared equally by the authors, absent an agreement otherwise. Each author of a joint work is free to enter into a non-exclusive license for the entire work, provided that the author issuing the license accounts to his or her coauthor(s). As a practical matter, licensees of music publishing rights often insist on obtaining approval on behalf of each author of a work even if the grant of rights is nonexclusive. Thus, the other copyright owners have the right to sell the work as long as they compensate you for it.
You should get a royalty based on the sales of the work, but this is something that should have been agreed upon in a contract or otherwise (e.g. oral agreement), I don't knoew if you have any agreement in place. The royalty amount is negotiable and may be either a percentage of gross or net sales or a fixed dollar amount based on unit sales.
If you sold/assigned/transferred your rights in the copyright there probably isn't anything you can do to stop the sales of the work. hope this helps
The broad bundle of rights that are associated with a musical copyright are known as "music publishing rights." These rights are not defined by statute but rather are terms recognized in the music industry. Similarly, the concept of the "writer's share" versus the "publisher's share" is based in practice, not law. Traditionally, 50% of the income derived from the exploitation of a composition is deemed to constitute the publisher's share and 50% the writer's share. Where the author assigns the copyright in the composition to the publisher, the publisher generally collects 100% of the income and, after deducting costs, remits the balance to the author.
"Mechanical rights" are the rights to include a composition in a sound recording. Once a song has been published, anyone can record it as long as the statutory mechanical license is obtained and the statutory fee paid. As of January 1, 2008, the statutory rate is 9.1 cents per composition or 1.75 cents per minute for songs over 5 minutes. This rate is subject to adjustments by the Copyright Royalty Board. Despite the statutory minimum, record companies will often insist on paying a rate that is less than the full statutory rate. A rate equal to 75% of the statutory rate is customary. This is true regardless of whether or not the songwriter has written all the songs on the album. Another common practice of the record companies is to limit the number of songs on a particular album for which the author is paid mechanical license fees even if the album contains a greater number of songs. Both the reduction in the mechanical rate and the limitation on the number of songs respecting which the record company will pay royalties is subject to negotiation.
Lawyer
5 years experience in intellectual property law