Why does not the laptop boot? (Ubuntu / Linux)?

I have a laptop HP 355 G2. Ubuntu was installed on a relatively small plate. I have the luxury of a large plate (1 TB) indulged, then installed a new Ubuntu, which worked well (at least seemed so). After switching off / restarting the laptop, however, the disk is not accepted as bootable; The Lappi does not boot.

A second new installation did not change the problem.

Where could the mistake be?

Additional question: Why is the USB mouse not recognized?

(My experiences are related to Windows, this is my first attempt to get to know Ubuntu / Linux (and if it annoys me, even the last one ;-))

Just calm ^^ We can do it… LOL

Did you use "use entire disk" and have it partitioned automatically?

If by hand, the mount point must be marked with / on the ext4 partition.

The problem has resolved (but does not really explain it to me): Have Ubuntu re-installed (ie a total of three times) and since then everything is done as it should have done from the beginning.

(However, the third installation process itself looked very different from the previous two - which apparently has done much more).