Should one search for a maid who ran away and left work after 20 days, in order to give her wages, knowing that she did not steal anything but threatened the employer, and six years have passed since the incident?

What the maid did by leaving the door open and using the phone for external calls, especially with young men, is a dereliction of duty and a betrayal of trust, and it is not permissible. It is better to forgive her, advise her, and give her what she is owed. You should search for her to hand over her dues. You have the right to deduct the cost of her external calls or the value of what she intentionally or negligently damaged. However, forgiveness and pardon are preferable, as Allah Almighty says: "So whoever pardons and makes reconciliation – his reward is due from Allah." You must be wary of oppressing a worker, for in the Hadith: "There are three whose adversary I will be on the Day of Resurrection... and a man who hired a worker and benefited fully from his labor but did not give him his wages." If you cannot find her, give charity on her behalf with what she is owed. If she returns, inform her, and if she is not satisfied, pay her what is due, and you will be rewarded.