For reference, I have Ubuntu LTS 18.04.1
If I ever leave my computer alone (so it enters sleep mode), the majority of instances it will not properly wake up if I hit the power button. That is, my computer makes noises as if it were going to wake up from sleep mode, but nothing happens on the computer screen - the light for the monitor is still yellow (as it is in sleep mode) rather than green (when my computer is really "on" and I can browse stuff, etc). This seems to happen if it sleeps longer than an hour, but I haven't really calculated this and it might just be my mind seeing things.
I tried looking around the internet for solutions, believing it was a usb issue, and implemented what ederopaa said (https://ubuntuforums.org/showthread.php?t=1968487). I did everything, but the first step where he said to comment out the first line (see the below but without quotes)...
"#echo US15 > /proc/acpi/wakeup"
"echo enabled > /sys/bus/usb/devices/4-3/power/wakeup"
I could not really do this as exactly written out though, because those lines didn't really show up in my /etc/rc.local. So within that file, I just added these two lines. For the last line of code he suggests I also used numbers relating to my mouse, but I'm actually not sure if that was the problem. In any case, this did not fix my issue, so I am here and would appreciate any guidance. Thanks!