The phrase "did a number on" usually means to cause damage or harm to someone or something. The antonyms for this phrase would be to repair, fix, or restore. If someone has done a number on something, they might need to undo the damage that was done. This could involve using tools or techniques to reverse the effects of the damage. Alternatively, the person might need to replace or repair the damaged item or area. By using these antonyms, people can focus on the positive side of things and work towards repairing the issues that have been caused.