Minecraft Launcher Stuck in Play Offline

Yesterday was just fine, I can still play online. But in the morning suddenly the launcher changed to play offline, I tried it and I still can play in multiplayer, but this afternoon, I tried it again after lunch, but I can't play in multiplayer anymore. I don't understand why, I tried doing a tutorial from youtube, I wanted to reinstall Minecraft but before I do that I thought on trying to ask here first rather than waiting to install Minecraft again. Please help, I really want to play Minecraft on Christmas with my cousins, thank you very much, have a nice day.