Trying to find my sons taxes I did for him on turbo tax.?

Each online return has to have it's own userID  so if you used the same userID for their return and then for your return you permanently overwrote the first return.  

To access your prior year online tax returns sign onto the TurboTax website with the User ID you used to create the account - https://myturbotax.intuit.com/

On the Tax Home webpage -

Scroll down to the section Your tax returns & documents.  Click on the Year and Click on Download/print return (PDF)

It's common to end up with multiple accounts. First LOG OUT of whatever TurboTax account you're logged into right now. Then use this TurboTax account recovery website to get a list of user ID's for an email address. Run the tool against any email addresses you may have used
https://myturbotax.intuit.com/account-recovery/