reinstall 18.04

[John R. Sowden]

My box is locking up for up to an hour with the head seek light on 
solid, mouse locks up

in a /var/log file I found about 900mb of error texts with no date or 
time, saying that

it could not find something and another error.  I want to "reinstall the 
operating system"

in ms language, bit I did not set up the home directory in a separate 
partition.

How do I do this.


tia,

john