I have preinstall windows 10 in my laptop. I have downloaded the latest version of ubuntu 64 bit. When I try to install from USB stick after reboot, it comes with error boot mgr missing, ctrl+alt+del to restart. I have downloaded the images multiple times still same error. Kindly let me know how can I resolve the issue.
Which software you used to create bootable USB.
Whether Rufus or isotousb.
Should clean your USB and format it by selecting NTFS format and select Windows bootable USB.
Than it will work. Did you check your lap bios boot manager. Whether it's configured USB to boot first.
And also I personally suggest you to try elementary os (Freya). It's also same as ubuntu. But the look and feel is different.