Hello and welccome to the forum
Krita is free and FOSS (free open source software) and you don’t have to pay at all.
I assume you bought it from the Microsoft store or a similar place?
Which version of krita are you using and which operating system?
What is the image size of the 3.4MB drawing that you ‘uploaded’ (Opened?).
What happened two weeks ago? Did anything change on your computer?
When you say, “… now everything doesn’t work anymore.”, what exactly do you mean?
Is it very slow? Do certain functions not work? Are some things missing?