After the installation of Ubuntu 12.04(or later) on Ideapad 8 series machines, there is a possibility to lose all other booting options other than Ubuntu (in Uefi booting there is an only option).
The symptom above may occur to the following systems:
All Ideapad 8 series with UEFI support
1. Enter bios F2 key and change option from UEFI boot to Legacy.
2. Save changes and restart PC (F10 key).
3. Enter Bios again and load default settings (F9 key).
4. Save changes and restart PC (F10 key).
5. All settings should be reset to defaults.
If all steps above fails BIOS need to be re-flashed.