I am not able to get my 2018 tax return form because I field under my parents account and now I am on my own

if your parents prepared their return after yours using the same account your return is permanently gone.  an account is only good for 1 return -the last one prepared.  an e-mail address can be used on up to 5 accounts.  if you are looking for your 2018 adjusted gross income so you can efile 2019, then you may be able to register at the IRS website to get a transcript of your '18 return which will have the AGI number

https://www.irs.gov/individuals/get-transcript

What You Need

To register and use this service, you need:

• your SSN, date of birth, filing status and mailing address from latest tax return,
• access to your email account,
• your personal account number from a credit card, mortgage, home equity loan, home equity line of credit or car loan, and
• a mobile phone with your name on the account.

What You Get

• All types are available online
• View, print or download your transcript
• Username and password to return later