[all variants] can't boot

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http://ubuntuforums.org – Hi people i really need help. Im a 14 year old noob so yea i screw things up a lot. Anyways, my laptop is a Lenovo U260 with specs so bad i feel like puking, so i have had windows 7 home premium installed at first, then i installed Ubuntu alongside with the windows 7. Afterwards i installed Linux mint and Fedora, which i then wiped out fedora from a partition of 40 GB in my hard drive. Then the GRUB 2 started to conk up, i cant't boot to anything, it always comes to a "error unknown filesystem. Entering rescue mode... Grub rescue>" and now im stuck there forever. The worst part i (Hardware)