I can't open the Minecraft Launcher

Hello, I have a problem. I turn on my computer, double click on Minecraft, but nothing happens. It just doesn't open the Minecraft Launcher.
When I opened Minecraft yesterday (it still worked) it wrote me some message, but I didn't read it, I know there was a BUY button! But I didn't read it and went to play. Again, when I wanted to play Minecraft, the Minecraft Launcher didn't open anymore. I don't know if it's a bug, or should I buy Minecraft again, and this was a trial version, although I could play on the servers with the original Minecraft. Summary: I double click on the Minecraft field, but the Minecraft Launcher field does not open. Please help me though so my username Girl_Catherine Thank you for understanding or help, best regards Catherine.