Is it possible to retrieve a terminated number if it has not been reissued?

Hi Mariah, if the line has not been resold, you can visit any MTN office closer to you and request to repurchase the line.
You can also check if the line is available to be reserved on MTN number search service.
Number search is a service that allows you search and reserve available numbers; Platinum or normal numbers from all existing number ranges from the comfort of your home.
How it works
 You will be able to search for numbers from https://www.mtnonline.com/personal/number-search/ using the prefix or by entering an exact number.
 Once the number is available, you will be able to reserve it by entering your details; name and and alternative number.
 As soon as the number is successfully reserved, you will receive a successful message with a token number.
 You are expected to visit the service centre within 72 hours of reserving the number with your token number as an evidence for the purchase of that number.
 A service centre agent can only activate a number for you once s/he confirms that the token number on your message is same as the token number on the system
 Please note that if the reserved number is not purchased after 72 hours, it will be made available again for other customers.