The correct answer is "wasn't used to". Here's why:
* **The sentence structure implies a change over time:** Tom didn't like using the computer in the past, but now he likes it.
* **The correct answer is "wasn't used to". Here's why:**
* **"wasn't used to"** means Tom wasn't accustomed to using a computer.
* **"didn't use to"** means that in the past Tom did not use the computer
* **"will get used to"** means that Tom will become accustomed to using a computer. This doesn't fit in this case
Therefore, the sentence would be: Tom **wasn't used to** using a computer, but now he enjoys it.