I always run my laptop on windows 7, which was already pre-installed. I used UnetBootin to install xubuntu 18.04 alongside windows 7 without a usb/cd. I don't have a usb/cd at the moment. I installed xubuntu, used it for a good two hours, installed lots of stuff, personalized it etc. and suddenly my browser freezed and it resulted in a over-all system lag. I had to force restart it. When i booted in again, i noticed no files that i created - nor the programs i installed with sudo apt install are there anymore. It simply "factory reset" my whole ubuntu files and i don't think there's a way to recover them anymore, so is there a way to prevent deleting all files from xubuntu at reboot?
all windows files are perfectly ok.
Is there a way to prevent this? Please. Also, please keep in mind i am not a fluent linux user, i just wanted to test it out. And suddenly this happened and i think i lost all my hope.