I downloaded the launcher, I logged in with the premium but I did it wrong and now that I want to do it again I press the premium button and it won't let me, I don't get anything or nothing appears
Please provide the launcher log. You can find them in
%appdata%\CCBlueX\LiquidLauncher\data\logsand search for the most up-to-date log where the error occourd. Please upload it here or paste the content of the log to https://paste.ccbluex.net/ and share the paste URL.
In case we cannot help you immediately: Try to use the "Offline login" instead and then proceed to login into premium account inside the client. Also be aware that it requires you to use a Microsoft account.
Today I updated the launcher with a few fixes to the microsoft premium login.