Can anyone explain why turbo tax constantly asks me to file a 2018 return if i already have done so with another provider. i actauly can not proceed without filing this

The only time that CRA asks you to file a previous year's return is if it was not received.  Can you please contact CRA directly to see if your 2018 was received and if not you will need to complete it before you can file your 2019 return.