If you're considering filing a lawsuit against your lawyer for malpractice, there are three elements that must be present for legal malpractice to have occurred:
Duty: The lawyer must have owed the client a duty of care. This means that the lawyer-client relationship was established and that the lawyer agreed to represent the client in a specific capacity.  For example, if you hire a criminal defense attorney, they owe you a duty of care to provide adequate representation in your criminal case.
Breach of Duty: The lawyer must have breached their duty of care to the client. This means that the lawyer did not meet the standard of care that is expected of attorneys in their specific area of practice.  Continuing with our criminal defense attorney example, if your attorney fails to show up to court or fails to file key documents in your case, they would be breaching their duty of care.
Damages: The breach of duty must have caused actual damages to the client. This means that if the lawyer's actions (or inaction) resulted in financial or emotional harm to the client, legal malpractice has occurred.
If, for example, you lose your job as a result of your case because your attorney missed an important court hearing, you would likely be able to prove damages.
Proving that your lawyer committed malpractice can be a complex undertaking. There are certain elements you must prove to have a successful claim, and not all instances of attorney misconduct will necessarily rise to the level of malpractice. If you think you may have a case against your lawyer for malpractice, contact an experienced attorney who can evaluate the facts of your case and advise you of your legal options.