As the other attorney said no response is required unless you are served in a law suit. If you unemployed and have essentially no assets they can't really do anything but make empty threats. Hopefully you will find a job soon. Then, review your debts and if you really can't handle them you may wish to file a Chapter 7 to great a "fresh start." Good luck.
You may wish to check with the Nevada Financial Institutions Division to determine if this debt collector is licensed to do business in Nevada. If not, you are welcome to file a complaint against them. Since you recently moved, you should be aware that the creditor could sue you in your former home state and then bring the court judgment to Nevada to enforce. You will also want to be aware of the laws in Nevada that are available to protect you should a judgment be entered. The link to these laws is below. Hope this perspective helps!
Are you sure the letter says they will seek a judgment against you if you don't dispute the debt? Collection letters are required to state that "if the consumer notifies the debt collector in writing within the thirty-day period that the debt, or any portion thereof, is disputed, the debt collector will obtain verification of the debt OR A COPY OF A JUDGMENT against the consumer and a copy of such verification or judgment will be mailed to the consumer by the debt collector." If this is what your letter says, it doesn't mean the collector is going to obtain a judgment against you. It just means if there was a judgment issued against you, requiring you to pay the money they're trying to collect, then they're required to provide a copy of it to you to prove they are allowed to collect from you. If they are threatening to sue you, you need to confirm they're licensed in Nevada to do so. A New York attorney that hasn't taken the Nevada Bar cannot sue in Nevada.
Ignoring the letter doesn't hurt you but it also doesn't help you. If they located your building, odds are good it was a technical error that they left off the suite number. If you don't owe the full amount on the collection letter, it's in your best interest to dispute the debt. Once you dispute the debt, the collector is required to stop all collection activities (including filing a law suit) until it can verify that you owe the debt.
I hope this helps. If I haven't answered your question completely or you have further questions, you can email me a copy of the letter to email@example.com, and I'll take a look at it for free.