Exporting .wxr not through wp-admin

I am trying to set up my WordPress site again as it broke down earlier and I no longer have access to the wp-admin panel (because the whole WordPress interface is corrupted, I still have the login credentials but I cannot get into wp-admin).

I want to export the existing site to .wxr to ease off the import process. I have access to the FTP, phpMyAdmin and Plesk.

Any advice appreciated. Thank you!