I changed my admin name and now all my files are gone…then I messed it up more.

Here is the Apple instructions for properly changing the user name:

Change the name of your macOS user account and home folder - Apple Support

The instructions must be followed exactly for every step (only one step is optional).

You must match up the short user name, the home folder name, and the path to the home folder. All three must match & be correct in order to have a working macOS user account and to regain access to your data.

If you cannot figure it out by using those instructions as a guide, then perform a clean install of macOS by first erasing the disk followed by reinstalling macOS & restoring from a backup. If you don't have a backup, then I would recommend using Carbon Copy Cloner (CCC) from the new working admin user account which will elevate CCC's privileges in order to access the files in the original user folder. Once you have a copy of your files, then perform a clean install & restore the files manually from the CCC copy. FYI, CCC allows you to store the files into a read-only .dmg archive file so you can easily store them on external media.....just make sure to open the .dmg file once you transfer it to external media to confirm you can access the files before you erase the Mac. Also, there is a filter option at the bottom of the CCC window which you can use to toggle on & off the files/folders so you can transfer just the items you want.

If you don't have a backup, then make sure to start having frequent and regular backups using Time Machine.