Windows 10 Creators Update (April 2017; version 1703) seems to have problems with Raster font in PowerShell and Command Prompt windows: launching either of these programs will display complete garbage instead of readable contents.
The usual DISM and SFC tools do not help here, but the fix is really easy.
First, open PowerShell or Command Prompt. Then open the window’s shortcut menu by clicking its small icon on the top left or by using keyboard shortcut Alt+Space.
Choose Properties from the menu.
In the Properties window, open the Font tab and choose anything but Raster Fonts (the cause of all evil in this case). Consolas at size 14-16 usually works best.
Click OK and behold the miracle: Windows PowerShell or Command Prompt scrambled characters are gone and you can now read the window contents! 😀
Update: please note that setting the font to Lucida Console does not survive restarts. This is a long overdue bug by Microsoft, so please use the Consolas font here.
Please note that this setting is retained only until the next shutdown or restart. To correct the setting permanently, open the window’s shortcut menu again by clicking its small icon on the top left or by using keyboard shortcut Alt+Space. This time, choose Defaults from the menu and repeat the font changing process (but please do not choose the Lucida Console font as explained above).
It’s like the quickest fix ever in the history of Microsoft Windows! 😛 But it does seem that the fault is on Microsoft’s side, as SFC and DISM do not repair the Raster Fonts.