I really don't know anything about programming language or so. I was trying to edit a usb pen drive partition but accidentally cleared ubuntu system disk partition. I later tried to boot the system and it kept failing to boot. I have a dvd which I used to install ubuntu 18.04 in the first place but it doesn't seem to work now. I tried many ways and found out two errors, swap/swapfile error and dependancy error. I don't have any idea how to fix it. Please help me. I have an important exam in about a month. I cannot afford a pc now.