The bank should have been given a specific case number when that attorney requested the account to be frozen. Contact the bank (visiting in person is best because you can more readily put them on notice that this may well be fraud if it isn't a mistake of identity) and ask them for the information. Tell the bank that you have already contacted the court in question and that the court has no record, and you wish for the bank itself to verify that there is or is not an actual judgment in place.
While I have never come across a case of someone freezing an account with a fraudulent (non-existent) judgment, I do know of a couple cases where attempts to collect on judgments were applied to the wrong person (e.g. the judgment was probably valid, but the collection in the judgment was made against a different person of the same name than the one the judgment was against). I also know of numerous cases of collection agencies committing outright fraud (and almost all of them are law office collection agencies ... lawyers know more about how to violate the law and get away with it, presumably) in various other ways, so it would not surprise me if fraudulent judgments are being done too. I cannot say what is going on in your specific case because I don't know enough about it.
If the judgment exists and specifically identifies you, you will need to have it vacated. You will need a lawyer for that. If you cannot afford one, you might qualify for free legal assistance at one of various legal clinics that might be in your area. You can also get free initial consultation from many lawyers.
If the judgment exists but names someone else, it can be just as complicated. See above about getting lawyer help.
But definitely be pro-active in putting the bank on notice that you believe the judgment to be false in some form (e.g. does not exist, or names someone else, or was fraudulently obtained without service).
If your employer does direct deposit to your account, be sure to have that stopped immediately. Likewise any other automated payments to you need to cease going to that account.
Do not judge the bank itself for freezing the account. Judge it instead on how well they act to help you through this. The law requires them to act in certain ways. If you find the bank does not do well to help you (for example, resisting providing the information needed for you to track down the problem), then by all means at the end of this, close the account and never bank there again. A good bank will work with you within their legal requirements.
With regard to the attorney's office, you did the correct thing by not providing them with any information. Did you get their address? If so, write them a letter demanding a copy of the judgment. Send the letter certified with return receipt and signature required. If you didn't get the address, call them again and demand it. The information from the bank should also provide this.
