Your friend left you alone to remotely fix her PC, and didn't share her password.  You took a break while a long-running utility completed, and when you returned, the screen is locked or the system went to sleep, and your friend is unavailable.  What to do?  Not much, unfortunately.  But keep these links handy to install a way to prevent lock outs next time.

The utilities enable you to override the power settings and / or screen saver settings by simulating activity on a Windows computer.  They run in the task tray and can be configured there.  Since most don't require installation, require little space and memory and have no license costs, these utilities make great additions to your portable tool kit.

Power Settings

Windows Power Settings optimize the use of electricity by automatically shutting down, moving to standy, or hibernating the system.  This isn't always optimal for remote support.  Fortunately there are some free, no-install utilities to address this.

Preventing Screen Saver Locks

Microsoft Windows can also lock the screen due to inactivity based on the screen saver settings.  Some utilities prevent this by periodically simulating keyboard or mouse movements.

Awake

Microsoft PowerToys Awake is "designed to keep a computer awake without having to manage its power & sleep settings." Unfortunately, Awake must be installed with all the Microsoft Powertools (i.e. it is not portable), and the download is large.

Caffeine

Caffeine from Zhorn Software simulates a keypress once every 59 seconds, so your machine thinks you're still working at the keyboard, so won't lock the screen or activate the screensaver.

Don't Sleep

Don't Sleep from Software OK is "a small Freeware Windows program to prevent system shutdown, Standby, Hibernate, Turn Off and Restart."  It can also be used to schedule shutdown and restart actions based on time, battery level, CPU load and / or network activity.  You can also use the app to "Please sleep" (turn off the display, etc.) under similar conditions.

Mouse Jiggler

Unlike the other utilities, Mouse Jiggler works by simulating the slight movement of a mouse. For reference, there are hardware devices that serve the same purpose.  But also unlike other utilities, Mouse Jiggler requires an updated .NET framework, which is unlikely to be installed on your friend's computer.  Although there is a portable version, it contains multiple files and requires much more space.

SwampGeek Recommends...

With the most functionality in the smallest, portable executable, Don't Sleep earns the SwampGeek Recommended seal of approval.