Reboot problem

[Susan HOPE]

Good Day
 
I have purchased Avast clean up and need to reboot the computer.  
 
Error keeps coming up: Boot failed
Am advised to file a bug against live Debian live image failed to boot.
 
Other info on screen:
/boot.log
 
/bin/sh/can't access
 
tty; job control turned off
 
Are you able to assist with clearing up this problem?
 
Thanks