Gather any other documents that pertain to the case the attorney handled, including bills from your attorney and the contract you signed. If your attorney is not returning your calls, send a letter specifying the reason why you called to create a paper trail. The remainder of the documents can be obtained during discovery after your new attorney files your malpractice case. Several states, including California, may view your file as your property, and not the property of the attorney. In these states the attorney is required to give you a copy of your case file. If s/he does not, you can file a complaint with the state bar association. Gather any and all documents that tend to support your claims of malpractice. List the names and contact information of any person who may have knowledge or have witnessed actions to support your claims of what the attorney did or the damages that were caused. Anyone who was involved in your original case should be included in this list, as well as anyone who witnessed interactions between you and your original attorney. Few attorneys accept legal malpractice cases, but those who do are highly specialized. You can find the ones in your area by contacting your state’s Bar Association or searching for legal malpractice attorneys in your state. Some states, such as California, have certified some lawyers as legal malpractice specialists. You will want to search for the attorney on the state's bar association public disciplinary database and check their ratings on lawyer ranking services such as AVVO before hiring. Most attorneys will offer you a free consultation. Bring your case file and any other pertinent documents so the attorney can determine if you have a valid malpractice case. You may be required to give your attorney money for costs before your malpractice suit can proceed, even if s/he is also being paid a contingency fee.  For most legal malpractice cases, your attorney will be paid on a contingency basis. This means they will collect between 30-50% of the proceeds of your award. These attorneys do not charge by the hour and will likely offer you a free consultation. If your attorney charges by the hour, s/he may not offer a free consultation. Your malpractice attorney will file the appropriate documents with the appropriate court and conduct discovery. S/he will also prepare you for deposition and/or testifying in a court trial.

Summary:
Obtain a copy of your case file from your attorney. Gather evidence. Make a list of people who could serve as potential sources of information or as witnesses. Contact a legal malpractice attorney. Schedule a consultation with the legal malpractice attorney. Follow your legal malpractice attorney's advice at all times.