Based on the situation you mentioned, you are indeed in a disadvantaged and wronged position, but you might as well try legal means. 1. You can find the person who sells the keyboard and ask him to make a statement or something, or ask him to testify in court; 2. You can find the buyer again and prove that the buyer and the person selling the keyboard are the same person; but these two This kind of difficulty is relatively high. If it is really "framed", it is basically hopeless. 3. You can respond to the lawsuit, but do not admit the facts and let the court decide.