I have deleted accidentally all disks partitions in the laptop, and now I cannot start ubuntu neither start installation from usb. After turning on laptop I get
error: no such partition.
Entering rescue mode...
grub rescue>
typing ls
I get
(hd0)(hd1)
I don't need to recover any data I would like to install new OS
When you reach grub rescue you are too late. During a boot you need to press a key (it differs for diff. BIOS; but ESC, F2, F8, F9, F10 are often used) to either enter bios where you pick your usb to boot from or to get a boot menu where you pick your USB to boot from.