Log in to your VPS via Remote Desktop. Please refer to how to reset password in windows VPS using RDP for more details.
1. Please login your rdp
2. Open SQL Server Management Studio.
6. Click on the [+] beside Security to expand the folder.
7. Click on the [+] beside Logins to expand the folder.
8. Double-click on the user login; [sa]. The properties window for the login [sa] opens.
10.Press OK.
11. Disconnect from the database instance.
12. Reconnect to the database instance using the SQL Server Authentication, the user name SA, and the new password.
NOTE: once reset the password if it's not working, please restart the SQL Server and check