Does anybody know why my username does not work this year and I had to make a new profile and now I cannot pull up my taxes from the last 3 years

If you entered your User ID exactly the same as when you created the account it will be available.  Maybe you entered a lower case letter when it should have been upper case or visa-versa.  Or a dash was entered instead of dot.  There could be many reasons.

I have had a User ID for the online editions for over 20 years and never had a problem.

Close all TurboTax windows on your web browser (including this one).  Copy and paste the account recovery website link onto a new web browser window and run the tool.

Use this TurboTax account recovery website to get a list of all the user ID's for an email address.  Run the tool against any email addresses you may have used - https://myturbotax.intuit.com/account-recovery

If none of the user ID's received will access your online account, then use the option shown in blue on the account recovery website, "Try something else"

If you used the desktop CD/Download editions installed on your computer, the only copy of your tax data file and any PDF's will be on the computer where the return was created.  TurboTax does not store online any returns completed using the desktop editions.

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