When I boot up my notebook PC from USB it shows me this: BOOTMGR is missing What could this mean? Please answer me.. I want to have Ubuntu! Thanks anyway..
The USB disk is not bootable. Please use proper method to prepare usb disk.
From Windows you can use following programs,
From ubuntu, you can use
Unetbootin is an utiliy that runs both Windows and Linux.
You can find a guide to properly install ubuntu on a flashdrive here https://help.ubuntu.com/community/Installation/FromUSBStick/