Minecraft Demo

Hello! I have bought Minecraft a couple of months ago and I have been enjoying it, but lately, I was playing Minecraft but it started getting really laggy so I closed the game and opened it again, but when I opened it, it says play demo instead of single player and multiplayer like usual. I tried closing the launcher and opening it again but it didn't work. I even tried deleting it and re-installing but it still didn't work. I looked everywhere on the internet for any solutions but none of them worked. I don't want my progress erased because I have been working and grinding for a long time. Please give me any solution that you think you could work. Thank you!