How do I print a copy of my 2018 complete return I'm only allowed 28 pages I need the full rwturr

Well those 28 pages  is the FULL return as filed ... but what you are probably looking for is all the worksheets that are not sent to the IRS ...

 To get whole return with all  the worksheets please log back in your TurboTax account and "add a state" to open the return back up (you are not really adding a state, just to open it back up), then select Tools, Print Center and choose the print center, then select returns and choose the radio button to include all worksheets.

Sounds like you may have a printer memory limitation. If so, print a few pages at a time/.

Good catch ... most home printers cannot retain 100+ pages in the memory ... so printing in smaller batches is required.