So yesterday I tried to play on my friend's server and it started as "Failed to login:Null" So I decided to log out and now the launcher said Buy now instead

So, long story short, yesterday after school I wanted to play minecraft together with my friend so I tried to join his server but It said "Failed to login:Null" so like other people I tried to log out of my minecraft account and log back in. So I did it but there was an issue, after logging in it said "Buy now" instead of Play. I also tried to login with other clients like Lunar but it didn't work. So I got a bit worried, there is also a person in the minecraft discord server that had the same problem so please help me and him ;-;. (my uncle bought the account from the website for my early birthday if u want to know)