My return was rejected. I tried deleting my dependent to see what difference that would make. Now I can't add him back on.

To add your Dependent back onto your return, you need to follow these steps in TurboTax Online:

1. Sign in to TurboTax and open or continue your return.
2. On the left panel, choose MY INFO
3. Click on the Add (Another) Dependent Box
4. Enter your dependent's information and complete the follow-up questions

Please see this TurboTax Article for more information regarding your reject: How do I fix e-file reject IND-517?