If you do not have a business you cannot deduct mileage for a vehicle.
I work with uber and door dash. I'm trying to complete my tax returns but i never got to a part where i could enter my mileage. did I miss something?
You have self-employed income and expenses so you must use the TurboTax Premium edition.
When entering your self-employed expenses there is a section for entering Vehicle Expenses where you can enter your business miles.
See this TurboTax support FAQ - https://ttlc.intuit.com/turbotax-support/en-us/help-article/import-export-data-files/enter-self-employment-business-expenses-like-home/L1k6HJY4A_US_en_US?uid=lv1i0k9p