My guess is your claim would be barred by the statute of limitations, but some statutes only apply to the time when you knew (or should have known) that you had a potential claim. I am not sure when that would be, in your case.
Who has the piano? Your mother?
There is also the potential problem of trying to collect any judgment that you win. If your mother does not have the money, you could win, only to not be able to recover. Depending on the nature of your estate, there *may* have been a surety bond. There is perhaps a chance that you might be able to collect on that. But there are WAY too many unknowns here to give you much constructive guidance. I would meet with a lawyer and see if there is anything you can do.
*** LEGAL DISCLAIMER I am licensed to practice law in the State of Michigan and have offices in Wayne and Ingham Counties. My practice is focused in the areas of estate planning and probate administration. I am ethically required to state that the above answer does not create an attorney/client relationship. These responses should be considered general legal education and are intended to provide general information about the question asked. Frequently, the question does not include important facts that, if known, could significantly change the answer. Information provided on this site should not be used as a substitute for competent legal advice from a licensed attorney that practices in your state. The law changes frequently and varies from state to state. If I refer to your state's laws, you should not rely on what I say; I just did a quick Internet search and found something that looked relevant that I hoped you would find helpful. You should verify and confirm any information provided with an attorney licensed in your state.
Statutes of limitations (generally 6 years or less) apply to most but not all claims. Exceptions can apply for such reasons as fraud or during a claimant's minority. Of course, no lawyer can advise whether you have a case w/o knowing a lot more details, but if only $3,000 and a piano are at issue, it may not be worth consulting a lawyer. You could bring a claim without a lawyer in Superior Court of New Jersey small claims court for Union County, which is right in Elizabeth, but the claim wouldn't succeed if barred by a statute of limitations. Maybe it would be worth paying an estates lawyer for a consultation to determine whether your claim may be barred by a statute of limitations,. Lawrence Friedman, Bridgewater, NJ. Certified as an Elder Law Attorney by the ABA approved National Elder Law Foundation, former Chair NJ State Bar Association Elder and Disabilities Law Section, Member Board of Consultors of NJSBA Real Property, Trusts & Estates Law Section, Vice Chair Special Needs Law Section of National Academy of Elder Law Attorneys, and Master of Laws (L.L.M.) in Taxation from N.Y.U. School of Law.
The statute of limitations generally runs out the later of a period of time, or two years after you have attained the age of 18 years. In some instances, the courts will, upon a showing of good cause, extend the statute of limitations (SOL) to two years after discovery. You have not indicated when you became aware of this bequest.
As Larry has noted, the amount in issue belongs in the small claims division, where you can represent yourself, assuming you can convince the court it should grant an extension of the SOL.
The last think to consider, is whether or not: (a) your mother is alive, (b) if she has the money to pay your bequest, and (c) whether you wish to terminate your relationship with your mother. If she is not alive or does not have money, you are wasting your time and effort assuming the SOL hass not expired.
The foregoing is not intended to be legal advice upon which you may rely as I have not been retained for this purpose.